The video is hosted by Dr. Paul Fisher of University of Florida IFAS Extension for the Five Tips for Horticulture series on the UF/IFAS Greenhouse Training Online channel (tinyurl.com/ufgto). The series highlights technical topics from university and industry experts. The channel is sponsored by the Floriculture Research Alliance (floriculturealliance.org).

For related training on this topic, see our Greenhouse Training Online certificate courses for growers at https://hort.ifas.ufl.edu/training, including the Irrigation Water Quality and Treatment course that will be offered in 2021.

The mission of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) is to develop knowledge relevant to agricultural, human and natural resources and to make that knowledge available to sustain and enhance the quality of human life. With more than a dozen research facilities, 67 county Extension offices, and award-winning students and faculty in the UF College of Agricultural and Life Sciences, UF/IFAS brings science-based solutions to the state’s agricultural and natural resources industries, and all Florida residents. ifas.ufl.edu | @UF_IFAS

“Our partnership with Scanit Technologies marks a major shift in how crop disease will now be managed,” said LumiGrow CEO, Jay Albere II.  “It all starts with empowering growers to take preventative action towards disease management rather than being forced to issue treatment actions when it’s often too late.  We’re now calling for growers interested in joining our partnership to develop custom strategies for their cultivation environments.”

The LumiGrow SporeCam^TM sensors (powered by Scanit Technologies) which are available to order from LumiGrow today, can capture, inspect, and classify harmful airborne spores for diseases such as Powdery Mildew and Botrytis.  The result is growers can optimize disease management practices, minimize yield losses, and monitor the effectiveness of their treatments.

But what does disease detection have to do with LED lighting?  LumiGrow VP of Research, Melanie Yelton informs us how smart lighting can also be used as an additional tool for responding to plant disease.

“Scientists have investigated the promise of light to reduce plant pathogen pressure since 1997.  Our growers have also long reported a noticeable reduction in the incidence of fungal and fungal-like pathogens in their crops under our smart LED fixtures.  Recent publications are now confirming this age-old hypothesis, and LumiGrow is bringing these unique lighting disease suppression strategies to market.”

Some of the publications Dr. Yelton is referring to include research institutions working directly with LumiGrow such as Cornell University.  These research centers are finding that specific light spectrum can inhibit the spread of spores for a large range of crops.

The way the new system works is through the LumiGrow wireless lighting control system named smartPAR^TM.  At the first notice of disease from the SporeCam^TM, your wireless control system adjusts the LumiGrow smart LED fixtures automatically to a spectrum targeted for disease suppression.  The grower then has the potential to gain time to implement a comprehensive disease management strategy.

The new feature is called smartPAR^TM Rapid Response and has also been made available to order from LumiGrow today.

“By integrating our SporeCam airborne disease sensor technology directly into the LumiGrow platform, we take a large step towards Scanit’s vision of a pro-active disease management solution.  This will be transformative for the indoor horticulture industry enabling sensing of early disease activity and dynamically suppressing spore activity,”  said Glenn Wanke, Chief Commercial Officer, Scanit Technologies, Inc.

Preventative disease management certainly has profound potential to bolster growers profit margins and even address some of the world food challenges we all face, but where did this technology come from?

Scanit Technologies has been deploying sensors in the US and Canada for the last three years.  Outdoor wine and table grape growers as well as cannabis, floriculture, fruit, and vegetable growers have begun using these sensors as Scanit continues to build their disease libraries.

“Our partnership with LumiGrow really illustrates the next age of agricultural technology,” mentions Glenn.  “When you’re on the cutting-edge of new technology, it’s critical that technology companies work in collaboration with growers to address these fundamental problems … together.  I couldn’t think of a better partner in the smart horticultural lighting space to bring our technology to market than LumiGrow.”

For growers interested in partnering their farm with LumiGrow as they develop the future of disease management enabled by light, contact LumiGrow today online at www.lumigrow.com or by phone at (800) 514-0487.

About LumiGrow

LumiGrow revolutionized horticulture in 2008 with the introduction of the first smart LED grow lights in North America.  Today, LumiGrow leads the world forward in grow light innovation with their TopLight and BarLight smart fixtures designed to maximize a growers’ profits.  The LumiGrow lights are wirelessly controlled by their smartPAR software to optimize yield, quality, and custom plant traits.  LumiGrow lights can be fine-tuned for greenhouse environments by pairing with their award-winning smartPAR Light Sensor to ensure consistent crop production year-round at the lowest energy cost.

LumiGrow has the largest install-base of smart LED grow lights in North America with installations worldwide.  For more information about LumiGrow, please see www.lumigrow.com

The Agriculture Improvement Act of 2018, commonly referred to as the 2018 Farm Bill, has legalized the production of hemp. The Agricultural Marketing Service (AMS) is the lead USDA agency to administer the new USDA Hemp Production Program. AMS, which is developing regulations to implement the 2018 Farm Bill provisions announced in the June 24, 2019, Federal Register that it expects to release a final rule in August

Growers in states that have already legalized hemp have been growing the crop according to their state’s regulations. Industry consultant John Dol at CannabiDol has been contacted by both greenhouse vegetable and greenhouse ornamental plant growers about switching to both hemp and cannabis.

“There are people who have been in the vegetable or ornamental plant industry who have made the switch,” Dol said. “There are also people who have been growing cannabis for some time and are looking to expand to a larger production facility.

“One of the challenges is not everyone has the ability/skill set from a managerial point of view. People in the greenhouse industry who have been exposed to managing people, crop scheduling and facility management have found it easier to make the transition to large scale cannabis production. However, specific cannabis plant knowledge will be stronger with the traditional industry players. I think a combination of both these factors in a management team will set a growing operation up for success.”

Differences in production scheduling

Dol said comparing ornamental plant and vegetable production operations, the ornamental growers have an edge in regards to planning because many vine crop vegetable growers only plant once a year.

“Greenhouse tomato growers plant their crops and then they basically maintain them,” he said. “Many greenhouse tomato growers in the Northeast are going to produce a mono crop which means planting in December or early January and then maintaining the same crop until November. Once the crops are finished, the old plants are removed, the greenhouses are cleaned and new crops are planted.

“Many greenhouse ornamental growers produce hundreds of different crops throughout the year. Similarly with cannabis there may be six cycles per year and there is a lot more planning involved with it. In terms of production scheduling, the transition to cannabis should be easier from the ornamentals side.”

Dol said depending on the cannabis strains being produced, there could be crop cycles every eight to nine weeks. Longer cycle times are available but will diminish overall yield.

“Most greenhouse growers, both vegetables and ornamentals, buy their starter plants from propagators,” he said. “In most cases, cannabis growers have to grow mother plants, cut clones and grow vegetative plants before flowering starts. These are all planning cycles that have to coincide with the flower room schedule. Cannabis production involves multiple grow rooms which makes the planning much more intense.”

Differences in labor intensity

When it comes to the differences in labor tasks involved with growing these crops, Dol said producing cannabis is between vegetable and ornamental crops.

“The work that has to be done with cannabis is less than what has to be done with a greenhouse tomato crop,” he said. “Producing a tomato mono crop for 10 months, the weekly labor tasks include pruning, lowering, deleafing and clipping every plant. That is just the maintenance labor that has to be done on the plants. There is also harvesting and packing.

“These tomato production activities happen from winter to fall five days a week. During the summer and early fall harvesting happens six days a week. A 24-acre greenhouse may have 300,000 plants in it. That is a lot of labor hours needed to produce a tomato crop.”

Dol said with cannabis crops there is less labor involved because there is less manipulation of the plants.

“There is a lot less labor involved with cannabis,” he said. “With cannabis once the plants begin to flower there may be three deleafings, harvesting and packaging. Depending on the production strategy, bigger cannabis plants take more labor and growers may want to do lower planting densities which involves having to bend the plants more. I prefer to have higher density plantings.”

Dol said greenhouse ornamental crops are the least labor intensive of the three crops.

“Unless the ornamental plants have to be pinched, disbudded or treated with PGRs and/or pesticides, the plants are put in the greenhouse, allowed to grow and then come out at the other end when their ready to sell,” he said.

Differences in pest control

Dol said greenhouse vegetable growers looking to produce cannabis have an advantage over ornamental growers when it comes to disease and pest control.

“Greenhouse vegetable growers have the edge because they have been exposed more to integrated pest management using biologicals and cultural methods to remedy these types of issues,” he said. “Since tomatoes are ready-to-eat products, most vegetable growers only spray as a last resort. This is something that also has application in cannabis production.”

Dol said with cannabis the control methods and products are regulated by individual states, which is one of the difficulties especially for companies with multi-state operations.

“Some states are stricter than others,” he said. “Some states may allow the use of natural oils like garlic oil or rosemary oil. Some states are allowing cannabis growers to use what can be applied to food crops. One of the issues is there hasn’t been a lot of product research done on cannabis because it has been an illegal crop for such a long time.

“For agricultural field crops there are many more acres in production so there are more pesticides and fungicides being used than in greenhouses. Greenhouse growers have always had a harder time getting products registered because there is not as much money in it for the companies developing and labeling the products. The cannabis production space currently is much smaller than the greenhouse vegetable or ornamental space. For the chemical companies it is very expensive and time consuming to have a product reregistered or relabeled for use on a specific crop. Now that hemp is legal, I expect more chemical companies will be looking at re-registering their products. If the hemp is used for medical cannabidiol (CBD), then the regulations are going to be stricter than if the hemp is used for fiber to make clothing or some other products that are not ingested.”

Learning the nuances of growing

Dol said he expects most of the greenhouse growers who are looking to start producing hemp are doing it for the production of CBD.

“If a grower wants to be a year-round producer, in most climates some kind of controlled environment is needed,” he said. “A greenhouse would be the best way to do that because the environment can be completely controlled. For growers producing only outdoors they may need to grow on many more acres to produce the same volume as in a greenhouse where production can occur year round. Water resources are used much less in greenhouses. And from a product quality/safety perspective greenhouses offer much more protection.

“Cannabis is a different plant than other crops that greenhouse vegetable and ornamental growers have produced before. All of the same factors, including light, water, nutrients and carbon dioxide that are required with tomato or mum crops, would apply to cannabis. It’s a matter of understanding what the plants need and also understanding from one cannabis strain to another the needs may be different. Most differences are in irrigation management and crop duration. There are nuances that have to be learned for the different cannabis strains.”

For more: John Dol, CannabiDol, cannabidol420@yahoo.com. 

This article is property of Urban Ag News and was written by David Kuack, a freelance technical writer from Fort Worth, TX.

Pests and plant diseases wreak havoc on crops worldwide, reducing major food crop yields by an estimated 10 to 40 percent. While all farmers are negatively affected by pests and pathogens, farmers in low-income countries lack resources to combat pest and disease and are more susceptible to crop loss.

In low-income countries, over 25 percent of crops are lost to pests and diseases. Monitoring and early detection programs can help lessen losses by providing timely and actionable insights on the severity and location of crop threats. This would allow farmers to mitigate losses and increase crop productivity if farmers apply a remedy with the first signs of disease emergence.

“Time is of the essence for farmers, especially those in low-income countries, when crops are threatened by pests and disease. The grantees are creating innovative tools that detect pests and diseases early, providing farmers time to respond and protect their crops and livelihoods,” said FFAR’s Executive Director Sally Rockey.

If their concepts are successful, the three individuals awarded this grant will have the opportunity to compete among a larger pool of applicants for a $1,000,000 prize to transform crop pest and disease surveillance globally.
Plants emit specific chemicals when attacked by insects or fungi. Dr. Hanseup Kim, associate professor at the University of Utah, received a $100,000 grant to develop chemical sensors that can operate for a long period of time in a resource-limited environment. These sensors will alert farmers to the different types and stages of crop damage.

Setting up existing pest incident monitoring networks in low-income countries is expensive and logistically challenging. Dr. Ritzvik Sahajpal, assistant research professor at the University of Maryland College Park, received a $99,723 grant to design a low-cost early warning system that combines machine learning algorithms, earth observation (EO) data and crop pest modeling to predict various crop threats. This system will be tested on maize and sorghum crops in Tanzania. The research team is also analyzing plant properties, temperature and soil moisture to estimate pre-harvest losses and determine crop losses from pests and fungi.

Traditional crop pest and disease monitoring approaches, like drones, are costly and limited in their ability to provide accurate data across large regions. Paul Wagstaff, senior agriculture advisor at Self Help Africa in Ireland, received a $97,400 grant to build an advanced algorithm that automatically analyzes satellite images for changes in leaf color and soil disruption to detect crop pests and disease. The “trained” algorithm is proposed to detect these subtle changes in satellite images, to allow pest damage to be distinguished from water and nutrient deficiencies and allow for rapid assessment of the degree of infestation across large areas, which to date has not been accomplished.

Foundation for Food and Agriculture ResearchThe Foundation for Food and Agriculture Research (FFAR), a 501 (c) (3) nonprofit organization originally established by bipartisan Congressional support in the 2014 Farm Bill, builds unique partnerships to support innovative and actionable science addressing today’s food and agriculture challenges. FFAR leverages public and private resources to increase the scientific and technological research, innovation, and partnerships critical to enhancing sustainable production of nutritious food for a growing global population. The FFAR Board of Directors is chaired by Mississippi State University President Mark Keenum, Ph.D., and includes ex officio representation from the U.S. Department of Agriculture and National Science Foundation.

OMRI listed and approved for organic production, Ancora contains a naturally-occurring fungus that infects both foliar and soil-dwelling pests such as whiteflies, thrips, aphids, leafminers, spider mites, grubs, and other pests.

The new Ancora is formulated on a different carrier which allows the product to mix more readily in water for easier sprayer application.

“The new Ancora is formulated on a diatomaceous earth granule which will make it easier to mix and then move through spray equipment without clogging filters,” noted Dr. Carlos Bográn, OHP manager technical service.

Growers using Ancora through a hydraulic sprayer can mix in water and spray.

“We still recommend growers using Ancora through a fogger allow the product to decant in water for 20 to 30 minutes before pouring in a tank and spraying,” notes Dr. Bográn.

The active ingredient in Ancora —Isaria Fumosorosea Apopka 97 strain, provides fast broad-spectrum activity on both foliar and soil insects in the greenhouse, nursery, and landscape markets. Ancora may be used on vegetables, herbs, certain fruits, and other crops.

Ancora carries a 4-hour Restricted Entry Interval (REI) and Caution signal word. OHP, Inc. is a leading marketer of pest control solutions for the greenhouse and nursery market.

One of the many challenges of tomato (Solanum lycopersicum L.) and kale (Brassica oleracea) greenhouse growers is the management of edema (oedema). Often described as intumescence or enations, edema is an abiotic-induced complication that develops at different levels of intensity
depending on the cultivar and, in some cases, between individual plants.

Symptoms

Edema is often described as a blister or callus-like formation that forms predominately on the bottom of leaves (Figure 1).

This swelling is the result of the epidermal layer on the leaf expanding due to cellular elongation, which eventually burst as cells reach their limits of expansion.

The resulting damage on the bottom-side of the leaf can be characterized by dark brown, tan, or even yellow necrotic tissue on the surface of the leaf that expands past the original location of the blister as a scab-like injury (Figure 2). On the upper side, necrotic spots mark the location of the ruptured intumescence below, while the surrounding tissue is generally
chlorotic (Figure 3). Tissue affected by edema is brittle, with the leaf structure cracking under gentle pressure by the fingers. Extensive edema can severely decrease the leaf’s photosynthetic capability and lead to senescence (Figure 4).

Causes

The cause of edema can be linked to a variety of environmental conditions. The long-standing suggested cause of intumescence is the buildup of excess
moisture in the root medium paired with conditions favorable to low transpiration (i.e. high humidity). In a study conducted by Kansas State in 20091, it was concluded that the water content of the root zone may influence the development of edema in tomatoes. Other research has pointed to light quality (lack of ultraviolet light) being a driving force behind the development of edema in Northern greenhouse tomato production. Due to largely overcast, low light conditions during winter months, most of the lighting provided to tomato crops in greenhouse operations are supplied by high pressure sodium (HPS) fixtures. While these units produce significant amounts of light in the yellow/red spectrum (550 – 650 nm), they lack in short wavelength energy (300 – 400 nm) (Figure 7). This shortwave energy is also lost in greenhouses constructed with glass glazing which has relatively low transmissivity of UV light as compared with polyethylene glazing.

In the same study by Kansas State, it was found that UVB helps prevent the formation of intumescence. In another experiment, conducted at the University of Arizona2, using small doses of end-of-day far red (EOD-FR) and a 75% blue light ratio led to a decrease of intumescence injury from 62-70% of leaves being symptomatic to only 5%. Work at Michigan State University3, found dramatically reduced edema symptoms when light with
50:50 Blue:Red ratio was used as compared with 100% Red light.

Edema of Kale

In kale, sudden increases in humidity can cause edema, often coinciding with outdoor weather like rain. Edema can be especially impactful on kale crops as the superficial appearance of leaves affects their marketability (Figures 5 and 6). Maintaining a low relatively humidity within greenhouse environments and changing management strategies to better cope with outdoor weather will help prevent edema in kale. This may include increasing shading within a greenhouse to reduce use of cooling pads to help manage humidity. Changes to irrigation timing and application or spacing plants further apart may also help to reduce humidity.

Solutions

Controlling the impact of edema should be done on a case-by-case basis for each operation and based on likely causes. As mentioned before, the severity of intumescence on tomatoes is largely dependent on the susceptibility of the cultivar and individual plants. If the crop is experiencing major leaf senescence and poor yields, it may justify the cost to invest in preventative measures. Most modern lighting fixtures with digital ballasts can run both high pressure sodium and metal halide (MH) bulbs. For older magnetic ballasts, conversion bulbs can be purchased that also allow you to utilize MH bulbs in an HPS fixture. While somewhat less efficient and shorter lived, the benefit of metal halide is it provides more of a “full-spectrum” light output, with significantly more short wavelength energy (Figures 7 and 8). This strategy combining HPS and metal halide could reduce the onset of edema-like symptoms. While a considerably costlier investment, LED fixtures offer the greatest flexibility in light quality. As prices decrease and efficiency increases, LED technology may offer the solution to improved yields through the reduction in intumescence frequency.

For many other growers, the prevalence of edema may not justify the investment of retrofitting an entire greenhouse. One preventative measure that can be taken to reduce the risk of edema is ensuring the proper environmental conditions of a greenhouse. This includes the ventilation of excessive humidity, proper use of supplemental lighting during periods of low ambient lighting, and irrigation management (to avoid saturating the root zone). It may also be beneficial to experiment with a variety of cultivars to screen for edema-like symptoms or work with a seed distributor on selecting cultivars that are less sensitive to edema. No matter the situation, it is advantageous to develop an action threshold to determine at what level of prevalence should you address the issue of edema in your operation.

Citations

¹Rudd, N. (2009). Environmental Factors Influencing the Physiological Disorders of Edema on Ivy Geranium (Pelargonium Peltatum) and Intumescences on Tomato (Solanum Lycopersicum) (Masters of Science). Kansas State University.

²Eguchi, T., Hernández, R. and Kubota, C., 2016. Far-red and blue light synergistically mitigate intumescence injury of tomato plants grown under ultraviolet-deficit light environment. HortScience, 51(6), pp.712-719.

³Wollaeger, H., & Runkle, E. (2014). Does light quality impact the development of edema? Retrieved from https://www.canr.msu.edu/news/does_light_quality_impact_the_development_of_edema

e-GROAlert
www.e-gro.org
CONTRIBUTORS
Dr. Nora Catlin, FloricultureSpecialist
Cornell Cooperative Extension, Suffolk County, nora.catlin@cornell.edu
Dr. Chris Currey, Assistant Professor of Floriculture
Iowa State University, ccurrey@iastate.edu
Dr. Ryan Dickson, Greenhouse Horticulture and
Controlled-Environment Agriculture, University of Arkansas, ryand@uark.edu
Nick Flax, Commercial Horticulture Educator
Penn State Extension, nzf123@psu.edu
Thomas Ford, Commercial Horticulture Educator, Penn State Extension, tgf2@psu.edu
Dan Gilrein, Entomology Specialist, Cornell Cooperative Extension
Suffolk County, dog1@cornell.edu
Dr. Joyce Latimer, Floriculture Extension & Research
Virginia Tech, jlatime@vt.edu
HeidiLindberg, Floriculture Extension Educator
Michigan State University, wolleage@anr.msu.edu
Dr. Roberto Lopez, Floriculture Extension & Research
Michigan State University, rglopez@msu.edu
Dr. Neil Mattson, Greenhouse Research & Extension
Cornell University, neil.mattson@cornell.edu
Dr. W. Garrett Owen, Floriculture Outreach Specialist
Michigan State University, wgowen@msu.edu
Dr. Rosa E. Raudales, Greenhouse Extension Specialist
University of Connecticut, rosa.raudales@uconn.edu
Dr. Beth Scheckelhoff, Extension Educator – GreenhouseSystems
The Ohio State University, scheckelhoff.11@osu.edu
Dr. Paul Thomas, Floriculture Extension & Research
University of Georgia, pathomas@uga.edu
Dr. Ariana Torres-Bravo, Horticulture/ Ag. Economics
PurdueUniversity, torres2@purdue.edu
Dr. Brian Whipker, Floriculture Extension & Research
NC State University, bwhipker@ncsu.edu
Dr. Jean Williams-Woodward, Ornamental Extension Plant Pathologist
University of Georgia, jwoodwar@uga.edu
Copyright ©2019
Where trade names, proprietary products, or specific equipment are listed, no discrimination is intended and no endorsement, guarantee or warranty is implied by the authors, universities or associations.

Published by e-Gro

Not all nutritional problems are caused by supplying too much or too little of a certain nutrient. “Tip-burn” of inner leaves is a common problem in hydroponic lettuce, where the margins of the young emerging leaves develop necrosis and burn as shown in Figure 1. The necrosis is from a calcium deficiency, but the actual problem is more the result of poor environmental conditions and water uptake. The lettuce in Figure 1 received an adequate supply of all plant essential nutrients in the hydroponic nutrient solution.

This e-GRO Edibles Alert article covers the cause of inner leaf tip-burn, how to differentiate tip-burn from other forms of marginal leaf necrosis, and best management practices to prevent inner leaf tip-burn during hydroponic production.

Inner leaf tip-burn is a physiological disorder involving calcium and water uptake

Calcium moves through plants passively and is carried with the flow of water. As plants transpire and take up water, calcium is essentially “pulled” up from the roots and throughout the plant. Rapid transpiration promotes calcium uptake and distribution within the plant. On the other hand, low transpiration rates decrease calcium uptake and transport.

The growing tip of lettuce is enclosed by leaves that make up the lettuce “head,” which block air movement and create a very humid micro-environment around the growing tip. This humid microenvironment results in low transpiration of the growing tip and reduces calcium
transport to the new leaves, even if the outer leaves are transpiring adequately.

With low transpiration to the growing tip, insufficient transport of calcium causes the tissue along the young leaf tips to collapse and turn necrotic as the leaves expand.

In this scenario, the problem is not insufficient calcium supplied to the root
zone, but a physiological disorder related to poor transpiration of water and humid environmental conditions.

A similar type of physiological disorder occurs with fruiting crops such as tomato, cucumber, pepper, and eggplant, but is called “blossom end rot.” Fruits have relatively low transpiration rates, and under rapid fruit growth and swelling, localized calcium deficiency occurs at the base of the fruit. The collapsed plant tissue also turns necrotic and resembles rotting as show in Figure 2.

Drought stress, high soluble salts, and chemical phytotoxicity can also cause leaf tip-burn in lettuce and other leafy greens.
However, symptoms of these problems tend to occur on older and mature leaves, whereas inner leaf tip-burn from poor transpiration and calcium transport occurs in young expanding leaves within the head.

Avoiding inner leaf “tip-burn” in lettuce

Unfortunately, there is no way to salvage necrotic leaf tissue. But there are
strategies growers can use to facilitate calcium uptake and prevent inner leaf tipburn.

Fertilize with adequate amounts of calcium.

First check that adequate calcium is supplied in the nutrient program. Supplying 40-50ppm of calcium in the applied fertilizer or hydroponic nutrient solution is a good starting point.

Depending on the source, the raw irrigation water may also contain calcium. Increasing calcium in the nutrient solution can help with calcium uptake and reduce inner leaf tip-burn problems, but remember the real problem is more often related to environmental conditions that affect water transpiration.

Calcium foliar sprays.

Weekly foliar sprays with calcium solution is a strategy to increase calcium concentrations directly in plant tissues. A starting rate is 400ppm calcium mixed using calcium chloride fertilizer salts (not calcium nitrate). Always trial on a few plants before the whole crop. This strategy can be labor intensive and may leave residues on leaf surfaces, and is not often used in commercial practice for lettuce.

Modify the growing climate.

Low relative humidity and air movement increase plant transpiration and facilitate calcium uptake. Consider manipulating the greenhouse heating and venting systems to dehumidify the air during cool and cloudy weather. Increase use of horizontal and vertical airflow fans to improve air movement (Figures 3 and 4). Conditions that promote rapid plant growth and leaf expansion promote inner leaf tip-burn, and shading/cooling under excessively high light and temperature conditions can help minimize risk.

Avoid antagonistic effects from other fertilizer nutrients.

High concentrations of ammonium nitrogen, potassium, and magnesium in the nutrient solution can block calcium uptake by roots. Tips to prevent nutrient antagonisms include limiting ammonium to 15% of total supplied nitrogen and maintaining the ratio of calcium:potassium at approximately 1:2 and the ratio of calcium:magnesium at approximately 2:1 in the applied nutrient solution.

Avoid high soluble salts.

High soluble salts reduce the ability for plants to take up water and calcium. If possible, maintain root zone electrical conductivity below 2.0 mS/cm.

Select resistant varieties.

Work with your seed supplier to select varieties specifically bred for lower susceptibility to inner leaf tip-burn.

e-GROAlert
www.e-gro.org
CONTRIBUTORS
Dr. Nora Catlin, FloricultureSpecialist, Cornell Cooperative Extension
SuffolkCounty, nora.catlin@cornell.edu
Dr. ChrisCurrey, Assistant Professor of Floriculture
Iowa State University, ccurrey@iastate.edu
Dr. Ryan Dickson, Greenhouse Horticulture and
Controlled-Environment Agriculture, University of Arkansas
ryand@uark.edu
Nick Flax, Commercial HorticultureEducator
Penn State Extension, nzf123@psu.edu
Thomas Ford, Commercial HorticultureEducator
Penn State Extension, tgf2@psu.edu
DanGilrein, Entomology Specialist
Cornell Cooperative Extension, SuffolkCounty
dog1@cornell.edu
Dr. Joyce Latimer, Floriculture Extension & Research
Virginia Tech, jlatime@vt.edu
HeidiLindberg, Floriculture Extension Educator
Michigan State University, wolleage@anr.msu.edu
Dr. RobertoLopez, Floriculture Extension &Research
Michigan State University, rglopez@msu.edu
Dr. Neil Mattson, Greenhouse Research & Extension
Cornell University, neil.mattson@cornell.edu
Dr. W. Garrett Owen, Floriculture Outreach Specialist, Michigan State University
wgowen@msu.edu
Dr. Rosa E. Raudales, Greenhouse Extension Specialist
University of Connecticut, rosa.raudales@uconn.edu
Dr. Beth Scheckelhoff, Extension Educator – GreenhouseSystems
The Ohio State University, scheckelhoff.11@osu.edu
Dr. PaulThomas, Floriculture Extension &Research
University of Georgia, pathomas@uga.edu
Dr. ArianaTorres-Bravo, Horticulture/ Ag. Economics
PurdueUniversity, torres2@purdue.edu
Dr. Brian Whipker, Floriculture Extension & Research
NC StateUniversity, bwhipker@ncsu.edu
Dr. Jean Williams-Woodward, Ornamental Extension Plant Pathologist
University of Georgia, jwoodwar@uga.edu
Copyright ©2019
Where trade names, proprietary products, or specific equipment are listed, no discrimination is intended and no endorsement, guarantee or warranty is implied by the authors, universities or associations.

Published by e-Gro

Downy mildew continues to be the most important disease of basil
throughout most of the USA, affecting plants grown outdoors at farms
and in gardens as well as in greenhouses every year. Widespread
regular occurrence of this devastating disease has clearly
documented that management is needed to ensure a marketable
crop. Below are some tips for management, an integrated approach
using multiple strategies listed below is recommended.

Management practices:

1. Start with pathogen-free seed.

Eurofins STA Laboratories in Colorado now tests basil seed for Peronospora spp. There may be other companies that offer testing. It is sufficient to test only at the genus level with this pathogen since it is the only species of that would be associated with basil seed.

Seed companies are starting to steam treat basil seed. Basil seed is not amenable to hot-water treatment because while in water the seed produces a gelatinous exudate, which makes the seed challenging to handle. One company known to offer steam treatment is High Mowing Organic Seeds.

2. Select resistant varieties.

Good suppression of downy mildew can be obtained with new resistant varieties that started to be marketed in 2018. They are the fruition of several years of conventional breeding by breeders working separately on this goal. It can take many crosses to obtain a plant with resistance plus all the desired horticultural traits that are in a susceptible variety, which include for sweet basil large, smooth, dark green, downward cupped leaves with good classic sweet basil flavor.

Devotion, Obsession, Passion, and Thunderstruck are the first resistant varieties released from the Rutgers University basil breeding program. They are marketed by VDF Specialty Seeds. Organically produced seed is available. Prospera is being marketed as organic seed by Johnny’s Selected Seeds.

Amazel is a Proven Winners variety, its seed is sterile and thus sold as cuttings. Limited suppression is typical with Eleonora, the first commercially available resistant variety. Emma and Everleaf (aka Basil Pesto Party and M4828Z) also have moderate resistance. Results and photographs from variety evaluations conducted at Cornell are available on-line at http://blogs.cornell.edu/livegpath/research/basil-downy-mildew/.

3. Avoid favorable environmental conditions for disease development.

The basil downy mildew pathogen needs humidity of at least 85% in the plant canopy to be able to infect. This disease can be controlled effectively by keeping humidity low. Practices to achieve this include base watering,
wide plant spacing, circulating fans, lights, and increasing temperature. Base heating is an especially effective method to reduce humidity. Set up sensors in the plant canopy to monitor humidity to ensure that the practices being implemented are sufficient. Fanning is a practice developed and being used in Israel for basil grown in protected culture. It entails directing
greenhouse fans toward plants so that leaves move. This prevents water depositing on leaves when humidity is high.

4. Turn lights on during night.

Illuminating either leaf surface of plants growing under protected conditions during nighttime was shown to effectively suppress downy mildew in basil by inhibiting spore production through a study conducted in Israel. Light was supplied in high tunnel-like structures with 20W Day Light fluorescent bulbs each equipped with a white metal reflector (30 cm diameter), with one bulb per meter row. Spores formed on leaf tissue shaded by other leaves, thus this procedure is most effective when plants are small. Initial experiments were done with illumination throughout night. Recent research has revealed light exposure is most important during the first 6 hours of night, and the pathogen needs at least 7 hours of darkness. Red light was shown to be the most inhibitory under laboratory conditions.

5. Apply fungicides.

A preventive program with conventional fungicides is considered necessary to achieve effective control when inoculum is present based on results from replicated fungicide evaluations. Ranman (cyazofamid; FRAC code 21) and Revus (mandipropamid; FRAC 40) have targeted activity for downy mildew and other oomycete pathogens. Their use is permitted in greenhouses. There are several phosphorous acid (phosphanate) fungicides labeled for this disease, including ProPhyt, Fosphite, FungiPhite, Rampart, pHorsepHite, and K-Phite.

These are suggested at low label rate tankmixed with Ranman and Revus, which are recommended used in alternation for resistance management.
Heritage (azoxystrobin; FRAC 11), Micora (mandipropamid; FRAC 40), Segovis (oxathiapiprolin; FRAC U15), and Subdue MAXX (mefenoxam; FRAC 4) are additional fungicides that can be used in greenhouse-grown plants
for retail sale to consumers. Subdue MAXX and Segovis use are on supplemental labels available in the CDMS database, supplemental labels can also be found on manufacturers’ websites (and, for those of you in NY, the NYS Pesticide database). Subdue can be applied once to plug-production trays after seeding and before seedling emergence and once after plugs are transplanted to larger pots; it must be tank-mixed with another fungicide labeled for this use. Heritage can similarly be applied only once at each production stage but both applications are to foliage and it must be applied in alternation with another fungicide. Micora and Segovis can only be applied to foliage of plants for retail sale as transplants; they are not permitted used on plants to be marketed as fresh herbs in grocery stores. Both can be applied at most twice to a crop. According to label directions, Micora can only be used in an enclosedgreenhouse with permanent floor. Segovis can also be used in outdoor nurseries. It is important to use a fungicide resistance management program including alternation among as many chemistries based on FRAC code as possible. Resistance to mefenoxam developed quickly in Israel demonstrating the capacity of this pathogen to develop resistance.

Basil downy mildew has proven difficult to manage with fungicides approved for organic production. This is partly due to the fact there
is no tolerance for any amount of disease on leafy herb crops for fresh consumption or for retail sale. Additionally, it is difficult to deliver spray material to the underside of leaves where the pathogen typically infects and produces spores. Most organic fungicides are contact materials. Thus far, none of the products tested in field evaluations have provided commercially-acceptable level of control. Results from research conducted on Long Island are posted at: http://blogs.cornell.edu/livegpath/research/basil-downy-mildew/.

There is no tolerance for downy mildew on basil for retail sale. Very few gardeners are going to apply fungicides to basil, and the products they can use have limited activity. Downy mildew can develop very quickly. I have
seen at garden centers basil plants that were very healthy appearing with some downy mildew sporulation and no leaf yellowing, but just three days later leaves on the plants not sold were yellowing and covered with spores
on the underside.

6. Monitor plants for symptoms.

Yellow leaf tissue in bands delimited by large veins is distinctive for basil downy mildew. It is important to examine the underside of leaves for the pathogen’s spores because there are other causes of leaf yellowing and spores can be present without yellowing. Additional photographs are posted at: http://blogs.cornell.edu/livegpath/gallery/basil/downy-mildew/.

7. Heat treat affected plants.

If symptoms are found early, it might be possible to save some plants by subjecting plants to heat and then taking steps to improve the management
program. High temperature is detrimental to the pathogen. Maximum temperatures for infection, colonization, and spore production are 80 – 88 F. Research conducted in growth chambers demonstrated that temperatures up to 113 F kill spores and mycelium of the pathogen in affected plants, with length of effective exposure decreasing with higher temperature range, least being 6 – 9 hours at 104 – 113 F. Subsequently solar heating has been used to cure plants in Israel by closing greenhouse vents or using a transparent IR polyethylene sheet covering during sunny days. It is recommended done at first sign of downy mildew and over 3 consecutive days with 3-4 hours exposure. It necessitates routine and close monitoring to ensure temperature reaches effective range while not rising high enough to kill plants. If temperature does not go above 95 F, treating for a fourth day is recommended. Given the potential for high temperature to damage plants, it is prudent to test the treatment on a small scale before implementing.

8. Promptly destroy unmarketable affected plants.

Affected plants should be carefully bagged (after turning off fans) and thrown out to minimize opportunity for spores to spread to other plantings.
More information about this disease plus images and links to monitoring pages are athttp://vegetablemdonline.ppath.cornell.edu/NewsArticles/BasilDowny.html.

Please Note: The specific directions on fungicide labels must be adhered to — they supersede these recommendations, if there is a conflict. Any reference to commercial products, trade or brand names is for information only; no endorsement is intended.

e-GRO Alert
www.e-gro.org
CONTRIBUTORS
Dr. Nora Catlin, FloricultureSpecialist
Cornell Cooperative Extension, SuffolkCounty, nora.catlin@cornell.edu
Dr. Chris Currey, Assistant Professor of Floriculture
Iowa State University, ccurrey@iastate.edu
Dr. RyanDickson Greenhouse Horticulture and Controlled-Environment Agriculture
University of Arkansas, ryand@uark.edu
Nick Flax, Commercial HorticultureEducator
Penn State Extension, nzf123@psu.edu
Thomas Ford, Commercial HorticultureEducator
Penn State Extension, tgf2@psu.edu
DanGilrein, Entomology Specialist
Cornell Cooperative Extension, SuffolkCounty, dog1@cornell.edu
Dr. Joyce Latimer, Floriculture Extension &Research
Virginia Tech, jlatime@vt.edu
HeidiLindberg, Floriculture Extension Educator
Michigan State University, wolleage@anr.msu.edu
Dr. Roberto Lopez, Floriculture Extension &Research
Michigan State University, rglopez@msu.edu
Dr. Neil Mattson Greenhouse Research &Extension
Cornell University, neil.mattson@cornell.edu
Dr. W. Garrett Owen, Floriculture Outreach Specialist
Michigan State University, wgowen@msu.edu
Dr. Rosa E. Raudales, Greenhouse Extension Specialist
University of Connecticut, rosa.raudales@uconn.edu
Dr. BethScheckelhoff, Extension Educator – GreenhouseSystems
The Ohio State University scheckelhoff.11@osu.edu
Dr. PaulThomas, Floriculture Extension &Research
University of Georgia, pathomas@uga.edu
Dr. Ariana Torres-Bravo, Horticulture/ Ag. Economics
PurdueUniversity, torres2@purdue.edu
Dr. BrianWhipker, Floriculture Extension & Research
NC StateUniversity, bwhipker@ncsu.edu
Dr. Jean Williams-Woodward, Ornamental Extension Plant Pathologist
University of Georgia, jwoodwar@uga.edu
Copyright ©2019
Where trade names, proprietary products, or specific equipment are listed, no discrimination is intended and no endorsement, guarantee or warranty is implied by the authors, universities or associations.

Sessions will focus on climate, insect management and pollinators, biostimulants and much more.

Speakers include Dr. Annette Wszelaki from Tennessee, Dr. Lori Hoagland from Purdue and Dr. Matt Ruark from Univ. of Wisconsin, and Purdue’s own team of experts.

If you are interested, please visit https://www.inhortcongress.org/

The education grant from AFE will help cover the cost of translating course materials into Spanish. This commitment to diversity training is critical. Even though approximately 80% of agricultural workers in the U.S. are of Hispanic origin and are Spanish‐speaking, there is a lack of Spanish language resources.

Lack of trained staff is recognized by growers as the number one issue they face. Training is an investment by businesses in their employees who are already performing well, have proven their work ethic, and just need opportunities to advance their growing careers. The AFE grant will also help measure the return on this investment, where UF instructors will quantify the impacts of learning in terms of knowledge, behavior, and economic value. The next course offered on October 1 is Disease Management, taught by Dr. Carrie Harmon.

Disease Management

After completing this course you will be able to:

• Prevent diseases by learning how diseases develop and spread
• Learn how to differentiate between disease and other issues
• Understand basic organic and conventional management options for greenhouse and nursery situations
• Safely apply and handle fungicides and understand rules and regulations

The course runs from October 1 to 26, 2018. It costs $US 199 per participant, and includes a personalized certificate of completion. Over 4 weeks, there are streaming video lessons, readings and assignments (about 2-3 hours total commitment per week), which can be accessed at any time of day. Taught by Carrie Harmon, Ph.D., Megan Brown, Ph.D., Rosanna Freyre, Ph.D.

Click here to register (http://hort.ifas.ufl.edu/training/).

Disease Management 2018 flyer

OTHER 2018 COURSES

For more information, go to http://hort.ifas.ufl.edu/training/, or contact us at greenhousetraining@ifas.ufl.edu.

BioBee has developed protocols for the integration of its beneficial insects and mites with selective pesticides under strict pest monitoring programs. These protocols can be used by conventional and organic growers of vegetables, fruits and ornamentals.

“BioBee believes that insects are the future,” said Rami Ben Dor, general manager at BioBee USA. “We are inspired by nature when we integrate our beneficial insects and beneficial nematodes into our growers’ IPM programs based on our 35 years of field experience and research and development.”

BioBee offers a variety of biological controls for some of the most common pests that infest both edible and ornamental crops, including spider mites, western flower thrips, sweet potato whitefly, aphids and leaf miners.

“Hort Americas has been looking to add biological controls and beneficial insects to its catalog for a few years,” said Chris Higgins, general manager at Hort Americas. “There has been an increasing demand for greenhouse-grown, pesticide-free products.”

Hort Americas partners with leading suppliers of commercial horticultural products from around the world to serve North American professional greenhouse and indoor growers with the latest technologically advanced products.

For more: Hort Americas, (469) 532-2383; customerservice@hortamericas.com;
https://hortamericas.com. BioBee USA, http://www.biobee.us.

If you want a recipe for how to specifically control insect pests, then you would best be served using conventional chemical pest management.

“When you look at things through an organic lens, it’s all about context,” said Michigan State University entomologist Matt Grieshop. “There are options to choose from, but your pest management choice is going to be dictated by your specific needs and circumstance. What works for one grower may not work for another for a whole host of reasons. You have to educate yourself about the system.

“It’s not as simple as putting a chemical in a tank and spraying. That is a very successful form of agriculture, but it is completely contrary to the philosophy of an organic system.”

Grieshop said there are two misconceptions when it comes to organic insect control.

“The average person on the street thinks that organic pest management is something that takes care of itself and growers don’t have to do anything. Which is absolutely bogus,” he said. “You are building a system that nature never would have thought up and that would never work in nature. Nature doesn’t work the way that agriculture works. So you are always going to have pest management issues of some sort. You’re going to have to do something.”

The second misconception about organic insect control is there are an infinite number of replacements to manage whatever pests growers may encounter.

“There are insect pests in Michigan that we struggle with every year just because we don’t have good control tools for them,” Grieshop said. “Pesticides exist because agriculture is unnatural and pests are inherently difficult to manage, especially on fresh produce.

“The tools for organic production are limited. You have to supplement that tool set with a lot of intelligence and experience. It is complicated and that is why not everyone is an organic grower. If it was easy, everyone would do it.”

Grieshop said organic pest management is not a one size fits all cure. That is chemical agriculture.

“The thinking behind chemical agriculture is I can grow whatever I want, wherever I want, whenever I want and to accomplish that all I have to do is apply a lot of petrochemicals and high energy inputs to make the system do what I want,” he said. “If I have a problem, I’ll spray with a chemical and kill what needs to be killed. In organic agriculture, it’s really about growing the right thing in the right space at the right time. This means you have to know more about what you are doing. If you know that you have a high incidence of an insect pest or a disease, then you choose a crop and a cultivar that are appropriate for the environment.”

Insect control choices

Grieshop said pest management for organic growers begins with preventive and cultural pest management.

“This means growing the right crop for the environment,” he said. “Choose cultivars that are resistant to your primary pest issues. Use good crop rotation. Try to do everything you can to create a favorable crop environment and an unfavorable pest habitat. If that doesn’t work then you move onto biological and physical inputs.”

Grieshop said for both field crop and controlled environment agriculture situations there are pesticides that are USDA-National Organic Program compliant. Products that are labeled for use on both these types of production systems include:

• Bacillus thuringiensis used primarily for lepidoptera pests.
• Spinosad-based products provide good control on soft-bodied insects and Lepidoptera caterpillars. Spinosad is a natural product derived from the soil bacterium Saccharopolyspora spinosa.
• Neem-derived products provide good control against soft-bodied insects and some pathogenic fungi.
• Beauvaria bassiana is a soil-borne pathogenic fungus that attacks soft-bodied insects.
• Nematodes are soil-borne roundworms that are applied to the soil and infiltrate the larvae of thrips and fungus gnats, cut worms and grubs. Grieshop said nematodes make good sense in a small scale system, especially if growers can produce them in-house. Michigan State and Cornell University have made videos on how to raise nematodes.
• Diatomaceous earth is a mined product that is effective against soft-bodied insects, including snails and slugs. These prehistoric calcium-based microbes have sharp edges that damage an insect’s exoskeleton leading to desiccation.
• Pyrethrum, a naturally derived chrysanthemum extract, is a broad spectrum, short residual neurotoxin that is effective mostly on soft-bodied insects.

Grieshop said the following controls are best used in greenhouse applications because they tend to disperse unless there is a means to contain them in an insect-infected area.

• Predaceous mites can be used against thrips and other plant-eating mites.
• Ladybird beetles are effective against aphids. Grieshop doesn’t suggest using the beetles for field agriculture because they tend to disperse unless there is a means to contain them in an insect-infected area.
• Lace wings are predaceous on larvae of primarily soft-bodied insects including aphids.
• Parasitoids and other predators can be purchased for specific insect pests. Grieshop said growers really need to know what insect pests they are dealing with before using these types of controls.

“All of the organic growers I work with actively try to foster biological controls in their plantings,” Grieshop said. “If you avoid spraying a lot of broad spectrum neurotoxins, you’re going to have more insect diversity in your system because you are not killing everything. Other things growers can do are to maintain flowering plants year-round and maintain the soil using cover crops. All of these things promote biodiversity in the production system and promote predaceous and parasitic insects. These practices may also promote pest insects too if growers aren’t sure of what they are doing. Shelter- and plant-based food sources are common resources for both beneficials and pest insects.”

OMRI-certified products

Organic Materials Review Institute (OMRI) is a nonprofit organization that works with input suppliers that service the organic market.

“Manufacturers and suppliers pay OMRI as a third party to certify their products are compliant with the National Organic Program,” Grieshop said. “These products include fertilizers, substrates, food preparation sterilants and pest management controls. Growers can look for the OMRI seal if they are buying organic inputs.

“However, for certified organic growers selling in an organic marketplace, the OMRI stamp does not guarantee 100 percent that the product can be used. Growers must confirm with their organic certifier if an OMRI-certified product can be used. Growers need to talk with their particular organic certifier before they make an application of any input.”

Grieshop said there will be times that a product has the OMRI stamp, but a particular certifier may not agree with an OMRI classification.

“The certifier has the final say on a grower’s farm as to whether or not something can be certified,” he said. “The certifier is not legally required to accept a product’s OMRI certification. However, nothing prevents the grower from going to a different certifier. And this is one of the many reasons growers choose a specific certifier.”

Comparing controlled environment, field production

Grieshop said controlled environment agriculture has more organic insect control options than field agriculture, but a lot of that has to do with the economics behind the two production systems.

“In a controlled environment such as a greenhouse or vertical farm, production space is considered by the square foot,” he said. “Making an economic decision about a CEA system, boils down to how many dollars is each square foot of production space worth? In a field crop environment, the typical thinking is in dollars per acre (43,560 square feet). Depending on the value of a square foot, in a greenhouse that might be 100 to 200 times more compared to a field-grown crop. That means the greenhouse grower can afford a lot more controls than a field grower.

“If a grower has 1,000 square feet of greenhouse space, and expects to make $50,000 off that space, that’s $50 per square foot of income that he’s protecting. If a grower is producing field corn, he might expect to make $4,000-$5,000 per acre. That is $5,000 over 43,560 square feet. What the field grower can afford to protect is a lot lower.”

Grieshop said a second difference in CEA is a greater amount of control over the environment and the control over the space.

“If a grower is going to release biological control agents in a greenhouse, he has a reasonable expectation that they are going to stay where he wants them to be active,” he said. “In an open field there are no such guarantees.

“Those are the two big functional differences. The gross economic value of the system and the ability to change things. Both of those factors essentially give CEA growers insect control options that would never be considered for open field culture. It doesn’t change the availability of those inputs, it just changes whether they are relevant.”

For more: Matthew Grieshop, Michigan State University, Department of Entomology, Center for Integrated Plant Systems Bldg.; (517) 432-8034; grieshop@msu.edu; http://www.ent.msu.edu/directory/matthew_grieshop; http://www.opm.msu.edu; http://msue.anr.msu.edu/topic/info/organic_agriculture.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Regardless of whether growers refer to using an integrated pest management (iPM) or integrated pest and disease management (iPDM) program, it won’t be successful if they don’t plan it out.

“Ironically, one of the biggest misconceptions greenhouse growers have with controlling pests and diseases is actually related to the success of their control programs,” said Karin Tifft , an integrated pest and disease management (IPDM) consultant. “If growers are doing a good job, it seems simple. But when things go wrong, they can go wrong in a big way.”

Tifft works primarily with greenhouse vegetable growers to develop IPDM programs. While she doesn’t yet have any ornamental plant growers as clients, she said she expects setting up an effective IPDM program for ornamentals would be more challenging because the whole plant needs to look good, not just the fruit. She said that ornamental growers actually have more natural enemies and chemical options than food crop producers.

“Microgreens and lettuce probably come the closest to selling the whole plant like with ornamentals,” she said. “ The difference is that microgreens and lettuce are such short term crops that there is not a lot of time for pest and disease pressures to build up as much. However, this does not mean proactive treatments, as in the release of natural enemies, are not needed. The greenhouse is never usually empty when growing lettuce and greens.”

Tifft said an IPDM program can incorporate multiple techniques, including cultural, chemical and biological.

“My specialty is what I call Bio-IPDM, biologically-based integrated pest and disease management,” she said. “I focus first on using natural enemies where I can. For the disease aspect, I look a lot at cultural control. This includes the ways disease can be prevented in the first place or limiting the spread and economic losses.”

Managing Greenhouse Diseases

Tifft said managing the greenhouse climate is the best way to manage fungal diseases. “Fungal diseases, in particular, usually have an outbreak due to something going wrong with the climate,” she said.

“Fungal spores, like Botrytis, are always present. But even though the spores are there, there is no disease outbreak.

“Growers have to be sure the greenhouse environment is not conducive to the expression of the disease. It is crucial that growers check their greenhouse environmental settings both by computer and by personal observation at various times during the day, including early morning and at night.”

Tifft said in the case of greenhouse tomatoes and peppers she doesn’t usually recommend making any proactive preventive fungicide applications for Botrytis. She will use them if Botrytis is spreading quickly.

“Disease control with cucumbers can be more challenging,” she said. “Growers should select powdery-mildew-resistant varieties to avoid having to apply fungicides too frequently. There are other cucumber diseases that are prevalent including Didymella bryoniae that causes gummy stem blight and Botrytis.”

Tifft said the greenhouse vegetable growers she is working with are currently applying chemical controls on an as-needed basis. She said for some of them there is the potential to move away from pesticides altogether.

“Growers considering aquaponics, which combines the raising of fish with plants, need to keep chemical applications at a minimum. Most pesticides cannot be used in an aquaponics system. This is a major consideration when growers think about this type of production system. Under these circumstances a grower would want to look at what he can do with cultural controls and natural enemies where there is no risk of anything getting into the water with the fish. This would also be the case with the growing of medicinal plants.”

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Tifft said based on her experience with the typical horticultural and agricultural crops there is going to be a place for pesticides for a long time.

“For vegetable growers it has become self-evident to many of them that they need to break the cycle of pests and diseases by emptying and thoroughly cleaning the greenhouse,” she said. “I have seen several cases where insect or disease problems have gotten out of control and there was no way to manage the problems other than to clear out the greenhouse. This may have occurred because of a change made to the IPDM platform. This could include a sudden drop in natural enemies or application of certain chemicals or because the correct action was not taken in a timely manner. The growers then attempted to do everything they could within the limits of the product labels, but weren’t successful at gaining control.”

Biological controls for insects

Tifft said most of the large greenhouse tomato growers in the United States and Canada are using natural enemies for insect control. She said in most of these operations the use of natural enemies is standard operating procedure.

The use of these biological controls has become easier because they have been well researched,” she said. “ There are effective natural enemies and reliable suppliers with good distribution networks which can deliver the biologicals overnight.”

Tifft said the use of natural enemies can be more difficult for the small grower because the cost of shipping can be prohibitive.

“Most natural enemies need to be shipped overnight,” she said. “For small growers, the cost of shipping may be higher than the cost for the amount of product that’s needed. And there usually is no way for growers to store the natural enemies without dramatically reducing their efficacy. They have to be used right away.”

Tifft is currently working with a small vegetable grower to evaluate the option of using banker plants to determine the feasibility of producing a steady supply of natural enemies. She said the banker plant system that is most established is for aphid control. Cereal aphids are introduced into the greenhouse on monocotyledonous plants (i.e., cereal plants such as rye, barley and wheat). The aphids serve as a food source for the parasitic wasp Aphidius colemani. The wasp, which reproduces on the cereal aphids, also feeds on several common greenhouse aphids. “

The banker plants allow for more reproduction and a consistent release of the parasitoids,” she said. “ There is a lot of potential to use banker plants with other hosts and predators.”

Ensuring a successful IPDM program

Tifft said every greenhouse grower, whether vegetable or ornamental, is using some sort of pest management platform, whether it uses chemical, cultural or biological controls. She said the thing that causes most of these programs to fail is quick changes.

“Consider an IPDM platform like a table,” she said. “If one of the legs of the table is kicked out, as in a change from a chemical to biological or biological to chemical platform, without putting in something to prop it up first, such as a new scouting plan or first switching to pesticides with less residual effects on natural enemies, the table will fall and the costs can be high. All of the changes to the platform need to be planned out. Each plan has to be tailored to the needs of the grower, the market, the crops, the climate and state restrictions.”

Tifft said she prefers that growers looking to incorporate biological controls into their IPDM programs first do trials in a separate greenhouse if possible. “

Ideally a grower would use a separate facility to avoid the effects of pesticide drift from another area,” she said. “Of course, this is not always practical. ere is a learning curve to using natural enemies, but IPDM when done correctly, will save money and lead to increased yields and higher quality fruit that sell for a better price. Reduced pesticide use also leads to fewer worker safety risks and less logistical challenges in terms of re-entry intervals.”

For more: Karin Ti , Greenhouse Vegetable Consultants; http://www.greenhousevegetableconsultants.com.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

In part three of our four-part series featuring Fox Greenhouses from Dallas Center, Iowa, Matt Fox humbly shares what you really want to know:
You’re a rookie if you…

1.Think you can grow through winter, without supplemental lights. Don’t even try it.
Either quit for the season, or invest in lighting. Consider perusing our sponsor Hort America’s website to learn about the advantages of LED lighting. 

2. Prune your plants into shock. Don’t shoot yourself in the foot.
Learn how to prune correctly. Do your research. Test a few plants. If you’re growing tomatoes, get tips here from Texas A&M. 

3. Wish away pests and diseases. It doesn’t work like that. Hit them head-on.
Expect to spend money for integrated pest management. If that’s a new term for you, read this. Interested in organic greenhouse production? Here are some resources. 

4. Fail to communicate with your customers.

image credit

I’ve mentioned it before, customer service is KEY in your greenhouse business. It’s part of why Matt is so successful. You don’t have to tell your customers everything. They don’t necessarily need to know your pump quit on you this morning. But they do need to know if a delivery is going to be delayed. Learn more about earning your place in your local market here.

5. Don’t ask for advice.
As I alluded to in the intro, I have a hard time asking for help. I’d rather eff it up without anyone watching. But when you’re growing for consumption, there’s no room for foolish pride. Seek advice from those who live and breath the industry. For instance, our sponsor CHiggins Consultancy. Now there’s a company who loves to talk about greenhouse growing.

If you’ve made mistakes, and are humble enough to share with us, we want to hear ’em! There’s no sense in not sharing. We’ve got a world to feed.
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Fox Greenhouses is located in Dallas Center, Iowa. Founder, Matt Fox has been growing pesticide-free, vine-ripened tomatoes hydroponically since 2000. Connect with them on Facebook.

If you missed the first two post in this series, read them here:

Post 1: 8 Grow Tips From a Cold Climate, Hydroponic, Greenhouse Tomato Grower

Post 2: Tapping Into Your Local Market: Ways to Build Relationships and Your Greenhouse Operation

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