The OSU Vegetable Production Systems Laboratory (VPSL) is pleased to be working with researchers at UC-Davis (A. Van Deynze) and The OSU (L. McHale, K. Mercer) to better understand and breed for yield under water and heat stress in bell pepper. The process will involve producing many seedlings of dozens of experimental lines (beginning with raw, untreated seed) and placing them in well- and minimally-irrigated field plots in CA and OH. A loose, peat-based rooting medium like often used on many Ohio farms and by the VPSL will not be used during seedling production. Instead, stabilized plugs provided by https://ihort.com/q-plug/ will be used. The VPSL is completing initial, small-scale tests with Q Plugs which, we are told, can produce seedlings that are stronger and field-ready in less time, and provide other attributes. Our initial impressions as we learn how to utilize Q Plugs most effectively are encouraging. We have appreciated their uniformity, ease of handling, ability to retain moisture without being wet, and the root growth they appear to facilitate. Q Plugs are available in different shapes and sizes and must be seated in matching prefabricated trays. Rigorous study is needed to verify but our preliminary, early-stage observations suggest that the ratio of root-to-shoot growth will be different and, perhaps, more favorable than when loose medium is used, in our experience. Using a stabilized seedling plug, it MAY be possible to transplant sooner and reduce transplant shock; however, these speculations must be properly tested. Pictures of young pepper seedlings in Q Plugs taken 3/1/25 are below. Please note that greenhouse temperatures were sub-optimal Jan 23 – Feb 6. Please contact https://ihort.com/q-plug/ or Matt Kleinhenz (kleinhenz.1@osu.edu, 330.263.3810) for more information.
Join us for an exciting new endeavor: the Tri-State High Tunnel School. This school is focused on high tunnel production and offers information to benefit commercial growers, beginning farmers, and educators, among others. Lunch is included with your registration.
Join us in person at one of several host locations:
Ohio – Piketon, Chillicothe, Wooster, Tiffin
Indiana – Goshen, Richmond
Michigan – Ann Arbor
Hosted by Extension Specialists and Educators from Michigan State University, Purdue University, and The Ohio State University.
OSU Extension is pleased to announce the 2025 Northern Ohio Vegetable Grower Winter Meeting will take place on March 4th, 2025.This program will provide opportunities to learn from and engage with OSU Extension specialists on various topics in vegetable production. The educational sessions include topics on crop protection against vegetable pests (insects, diseases, weeds), high tunnel management, safeguarding water quality, and more. Take part in this educational opportunity to help equip you with the knowledge you need to help improve vegetable production on your farm.
AGENDA:
9:00: Welcome/Weed Control in Sweet Corn & Pumpkins
Chris Galbraith, OSU/MSU Extension
9:35: What’s New in High Tunnel Production and Potato Varieties
Matt Kleinhenz, OSU
10:20: Break
10:30: Soilborne Disease Management in Tomatoes
Andres Sanabria Velazquez, OSU
11:00: Preserving Water Quality in the Western Lake Erie Basin
Jocelyn Ruble, OSU Extension
11:30: Cover Crops for Weed Control in Vegetables
Ram Yadav, OSU
12:00: Lunch
12:45: Pepper Insect Pest Control/IPPM in Cucurbits
Ashley Leach, OSU
1:30: Vegetable Diseases of 2024: Diagnostic Lab Recap
Francesca Rotundo, OSU
2:00: Use of Spray Drones in Vegetable Production: Challenges & Opportunities
Erdal Ozkan, OSU
2:30: Evaluations/Credits
The program will run from 9:00am-2:30pm, with check-in beginning at 8:30am. Registering online prior to the event is required to ensure there is room. The event will take place at The Neeley Center at Terra State Community College (2830 Napoleon Rd, Fremont, OH 43420).
This event is free and will include a catered lunch. This event is worth 3 ODA credits for Commercial category 2B (category 3 for Private) and 0.5 credit for Commercial category 1. Vegetable growers won’t want to miss this opportunity to learn from and connect with fellow growers, extension staff, and other individuals working within the vegetable industry.
Visit the link below to register for this event:
Go.osu.edu/nwveg
Please reach out to Chris Galbraith at galbraith.108@osu.edu or 734-240-3178 with any questions.
This article was originally posted on Michigan State University Extension News.
The Great Lakes Expo (GLEXPO) is the premier fruit, vegetable and farm market expo in the Midwest. This annual event features educational sessions on important industry topics, a large trade show for networking and discovery, and other specialized workshops and meetings. This convention has been held annually since 2001 and has been a consistent favorite among growers and other ag professionals across the country.
Each year the event features a robust agenda of vegetable programming organized by Michigan State University Extension. The educational presentations cover a wide range of crops, offering something for everybody when it comes to learning about new developments in the vegetable industry. Many of the sessions are also worth Michigan and Ohio restricted use pesticide (RUP) credits and certified crop advisor (CCA) credits in various categories.
The event will be held at the DeVos Place in Grand Rapids, Michigan from Dec. 10-12, 2024.
The following is further information on the vegetable sessions offered at the Expo this year. These are highlights for vegetable producers and is by no means the complete program. Many other educational sessions centered on fruit, greenhouse production, farm-marketing and other areas of specialty crop production will be offered as well. To view the full agenda and to find more information, please visit the GLEXPO website.
Tuesday, December 10, 2024
Pickles and Vine Crops: 9:00 a.m. – 11:00 a.m.
Pest Management in Cucurbits with an Emphasis on Pollinator Protection
Laura Ingwell – Purdue University
Houghtaling Farms: Our Experience Growing Cucumbers and Pumpkins. Challenges and our Strategies
Mike Houghtaling – Houghtaling Farms
Trends from the Vine Crop Seed World
Dana Hilfinger – Johnny’s Selected Seeds
Downy Mildew Update
Mary Hausbeck – Michigan State University
Asparagus: 9:00 a.m. – 11:00 a.m.
Asparagus Beetle Management
Zsofia Szendrei – Michigan State University
Purple Spot Update
John Spafford – Michigan State University
Mary Hausbeck – Michigan State University
Irrigation and Calcium Interactions in Asparagus
Zack Hayden – Michigan State University
Progress Towards Predicting Asparagus Emergence
Dan Brainard – Michigan State University
Brassicas:9:00 a.m. – 11:00 a.m.
Tips and Tricks for Summer Harvested Broccoli and Cauliflower
Ben Phillips – Michigan State University Extension
Diversifying Weed Management Strategies for Improving Weed Control in Cole Crops
Thierry Besancon – Rutgers University
Lessons Learned Growing Cauliflower, Broccoli, and Baby Kale on a Commercial Scale
Jon Dinsmore – Dinsmore Farms, Inc.
Managing Insect Pests in Brassica Crops
Zsofia Szendrei – Michigan State University
Photo by Getty Images
Sweet Corn:2:00 p.m. – 4:00 p.m.
Managing Insect Pests in Sweet Corn
Zsofia Szendrei – Michigan State University
Wildlife Management Strategies in Corn
Olivia Smith – Michigan State University
Evaluating Tools to Manage Sweet Corn Tar Spot in Central Wisconsin
Amanda Gevens – University of Wisconsin-Madison
Sweet Corn Weed Control Begins With the Weeds
Mark VanGessel – University of Delaware
A Primer on Aster Yellows and Testing in 2024
Jan Byrne – Michigan State University
Researching Root Lesion Nematodes in Carrots and More
Marisol Quintanilla-Tornel – Michigan State University
Lance Fosberg – Michigan State University
Getting the Most from your Carrots Through Beneficial Root-microbial Relationships
Lori Hoagland – Purdue University
Photo by Getty Images.
Soil Health and Cover Cropping:2:00 p.m. – 4:00 p.m.
Promoting Beneficial Microbes with Biocontrol Capabilities in Tomato Cropping Systems
Lori Hoagland – Purdue University
Managing Nematodes with Soil Amendments in Vegetable and Fruit Crops
Marisol Quintanilla – Michigan State University
Soil Health Strategies at Providence Organic Farm
Ryan Romeyn – Providence Organic Farm
Cover Crops for Weed Control and Other Goals
Katrina (Kat) Becker – Cattail Organics
Wednesday, December 11, 2024
Mushrooms:9:00 a.m. – 11:00 a.m.
How We Do It: Wild Foraging
Aaron Grenchik – Great Lakes Treats
How We Do It: Outdoor Production
Rich Leep – Leep Mushrooms
How We Do It: Indoor Production
Chris Swinson – Mycophile’s Garden
How We Do It: Marketing
Jill Grenchik – Great Lakes Treats
Rich Leep – Leep Mushrooms
Chris Swinson – Mycophile’s Garden
Onion:9:00 a.m. – 11:00 a.m.
Stemphylium Update
Mary Hausbeck – Michigan State University
Onion Weed Control and IPM – An Ontario Perspective
Wendy Zhang – Kejay Farms
New Onion Weeds and their Seeds
Dan Brainard – Michigan State University
Jordan Hoekstra – Vriesland Growers Cooperative, Inc
Onion Thrips Research Update
Zsofia Szendrei – Michigan State University
Tomato Pepper Eggplant:9:00 a.m. – 11:30 a.m.
Soil-biodegradable Plastic Mulch: Should you Make the Switch?
Shuresh Ghimire – University of Connecticut
The Secret Sauce: How We Add Value to Chili’s in a Northern Climate
Nate Mehren – Fat Baby Hot Sauce
Innovative Bed Designs for Tomato Production: Analyzing Soil Fumigation and Irrigation Patterns
Emmanuel Torres Quezada – North Carolina State University
How We Do It: Grafting, Steaming, and Soil Disinfestation
Ernest Zimmerman
Terry Zimmerman
Systems of Machinery for Any Scale, with a Focus On Controlling Weeds
Sam Oschwald Tilton – Glacial Drift Enterprises, LLC
Your First Date with the Soil-making Good Observations and Soil Testing
Vicki Morrone – Michigan State University
Pest Management in Protected Culture With Emphasis on Biological Control
Laura Ingwell – Purdue University
Organic Meet and Greet
Julie Studier – Tower Hill Farm
Ryan Romeyn – Providence Farm
Katie Brandt – Michigan State University
Potato:2:00 p.m. – 4:00 p.m.
Potato Insect and Pest Management for Market Growers
Ray Rantz – Michigan State University
Zsofia Szendrei – Michigan State University
Potato Disease Management for Market Producers
Jaime Willbur – Michigan State University
Irrigation Management and Efficiency in Potato Systems
Younsuk Dong – Michigan State University
Lyndon Kelley – Michigan State University & Purdue University
Nematodes in Potato Systems – Is Compost a Solution?
Marisol Quintanilla – Michigan State University
Celery: 2:00 p.m. – 4:00 p.m.
Carrot Weevil Control
Elizabeth Long – Purdue University
Update on Celery Meltdown Research
Douglas Minier – Michigan State University
Mary Hausbeck – Michigan State University
Primer on Aster Yellows and Leafhopper Testing in 2024
Jan Byrne – MSU Plant and Pest Diagnostics
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Registration is open now. Make a plan to attend GLEXPO this year to learn and connect with fellow vegetable growers, university and extension staff and other ag service providers from all around the country. You never know what new ideas or opportunities you will find at the annual Great Lakes Fruit, Vegetable and Farm Market Expo.
Whether growers are creating, discovering, or connecting with previously untapped markets, much is happening in Ohio annual specialty crop production that affects when crops are established and harvested and how they are managed in between.
For example, growers working with increasingly diverse markets must provide vegetables, flowers, herbs, and other crops meeting specific standards for size, color, weight, and other characteristics. Evolving standards continue to alter the mix of crops consumers/customers seek and/or their form – steadily rising interest in crops enjoyed around the world, micro or baby greens, small potatoes, and personal size melons are four common examples among many others.
Also, some markets are looking for Ohio or regionally grown products over more of the calendar year, challenging historical perspectives on seasonality.
Questions about seeding and transplanting dates naturally follow from these developments, especially since Ohio growers: (a) operate in locations with variable growing conditions and (b) use open field and/or semi-protected systems featuring low, mid, and/or high tunnels, creating additional complexity and opportunity.
Typical basic practice is to circle target harvest dates and confirm expected crop maturity, then count back to ideal seeding or transplanting dates, estimating based on likely near crop environments and other factors. As such, possible crop responses to light-temperature combinations expected to occur from seeding/transplanting onward are key. Selecting proper seeding/transplanting dates when only natural sunlight will be available relies on a few key principles.
For example, “growth” is defined as an increase in the amount of plant biomass whereas “maintenance” refers to the persistence of that biomass. Growth tends to require more light than short-medium term maintenance. This is one reason why established or harvest-ready crops can be maintained for weeks to months in various settings in fall-winter after growth has stopped due to much shortened days. Indeed, getting crops to market-ready status before growth stops due to inadequate light availability then maintaining them in saleable condition for weeks after is a core goal for many who produce and market fall-winter. Others look to get crops to a stage allowing them to overwinter successfully then complete growth and mature in early spring. Still others who also want to be first to the new year’s markets want to know how early seed or transplants can be set in late winter to utilize every available part of the expanding growth period. In all cases fall-to-spring, optimal temperatures help plants utilize whatever light is available but warm temperatures cannot fully replace or make up for low levels of light. In fact, high temperatures when light levels are unable to support growth are usually detrimental. This is one reason why some growers ventilate to cool their crop-filled high tunnels during clear but short days winter and early spring.
Crops differ widely in the amount of light (intensity x duration) required for them to grow. One rule-of-thumb is that most crops produced with sunlight only require at least ten hours of daylight to grow. Daylengths in Ohio are ten hours or longer between January 27 and November 14, on average. (You can see year-round daylengths at your location at https://www.timeanddate.com/astronomy/usa). Therefore, it is reasonable: (a) to target November 14 (on average) as the date by which most fall established crops should reach saleable condition and (b) to expect crops seeded or transplanted around January 27 (on average) to grow at rates tracking the increasing daylengths; i.e., very slowly at first and increasing as light levels increase. However, there are two important exceptions to these rules-of-thumb. First, some crops can grow when using sunlight alone when daylengths are less than ten hours but need to be identified carefully. Second, as mentioned earlier and shown in https://u.osu.edu/vegnetnews/2024/02/03/a-minimalist-approach-to-ensuring-fall-through-spring-vegetable-harvests/, https://u.osu.edu/vegnetnews/2024/02/17/high-tunnel-crop-and-market-period-diversity/, and grower experience, mid-late fall can be an excellent time to establish crops able to over-winter and mature early the following spring (e.g., garlic, carrot, some Brassicas), before or while new crops are being seeded/transplanted. Crops with this ability can further expand harvest and marketing periods.
Seeding/transplanting windows for many annual specialty crops expected to be harvested in 2024 or early in 2025 from naturally lit open field, or low, mid, and/or high tunnel plantings remain open but informed steps should be taken soon to utilize the time that remains.
This article was written by Dr. Francesca Rotondo.
Bacterial canker (BC), caused by Clavibacter michiganensis, affects both tomato and pepper plants. The disease is seedborne and can be introduced through infected seed or transplants. It spreads through mechanical transmission during pruning and other field or greenhouse operations. The bacterium thrives with high humidity and warm temperatures, and heavy rainfall further contribute to its spread and secondary infections.
In tomatoes, bacterial canker is more severe because the bacterium invades the vascular system. Early symptoms include stunting and wilting, followed by open cankers on the stem. When stems are split open, a thin, reddish-brown discoloration is visible in the vascular tissue, especially at the base and nodes. Secondary symptoms include browning of leaf edges (“firing”), upward curling of leaflets, and small, tan fruit lesions with a white halo, known as “bird’s-eye” spots. (Figure1)
In peppers, the infection is not systemic. It primarily causes foliar symptoms and affects fruit, leading to yield reductions (Figure 2). Canker-infected pepper fields can also serve as sources of inoculum for nearby tomato fields.
Figure 1. Characteristic symptoms caused by bacterial canker in tomato: wilting (A), vascular discoloration (B) and bird-eye lesion on fruit (C
Figure2. Typical symptoms caused by bacterial canker on pepper leaves (A) and fruits (B)
Managing bacterial canker is challenging once it is present. Prevention and sanitation are crucial for an effective management:
• Start with certified and disease-free seeds and transplants
o sanitize seed using hot-water treatment (ohioline.osu.edu/factsheet/hyg-5818).
• Disinfect all tools and equipment to prevent contamination
• Regularly scout for symptoms, and destroy infected plants
• Rotate crops, avoiding tomatoes in infected fields for 3-4 years
• Ensure fields are free of weeds or volunteer tomato plant
• Reduce stresses with balanced nitrogen, improved soil organic matter, and well-drained soil
• Copper fungicides and streptomycin should be applied before transplanting to the field, and copper fungicides can help slow the disease’s progression during the growing season
In 2019 and 2021, the Vegetable Pathology Laboratory (Dr. Sally Miller and Dr. Francesca Rotondo) conducted trials to assess the natural resistance of different pepper varieties (bell pepper, banana, and jalapeño). In 2019, the percentage of marketable fruits was significantly higher in jalapeño and banana varieties compared to bell pepper (80% vs. 60%) (Table1a). In 2021, chili varieties had the highest percentage of marketable fruits (95%), followed by jalapeño (88%), banana (82%), and bell pepper (75%) (Table 1b).
Table 1: results from the field variety trials conducted in 2019(a) and 2021 (b)
In 2021, the Vegetable Pathology Laboratory also evaluated the efficacy of biorational products against bacterial canker in pepper seedlings in two independent greenhouse trials. Theia, Regalia (giant knotweed extract), and Howler reduced BC severity by 78%, 73%, and 68%, respectively, in the first trial. Similar results were observed in the second trial, with Regalia, Howler, Theia, Vacciplant (laminarin), and Stargus (Bacillus amyloliquefaciens F727) reducing disease severity by up to 80% This research was funded by the Ohio Vegetable & Small Fruit Research & Development Program (OVSFRDP).
Tomato production dominates main season, summertime high tunnel use but presents challenges. Like an increasing number of growers, we experiment with ways to maintain high tunnel soil productivity and profit potential for the long-term. Our operating principle is that crop and market diversity are useful and while some crops offer less income potential, their contribution to the success of the farm may not rest entirely in their specific balance sheet. Our posts on 10/28/23, 2/17/24, and 7/27/24 provide additional information and highlight some of our recent and ongoing work focused on ensuring year-round success in high tunnel production. Recent activities involving butternut squash, a mixed-species summer cover crop, and various vegetable and flower crops are summarized below.
Three panels focused on a mixed-species summer cover crop (cowpea, Italian ryegrass, pearl millet, and sorghum-sudangrass) seeded on 6/5/24 and terminated on 8/20/24.
High tunnel growers have long used standard 6 mil poly film to cover their structures. Standard 6 mil poly film is the “covering” workhorse of the high tunnel industry. However, as most high tunnel growers know, standard 6 mil poly film can be punctured easily, will continue to tear if cut, eventually becomes brittle and less transparent, retains very little heat energy, and allows sunlight to escape the high tunnel without contributing to photosynthesis, which hampers growers wanting to maximize growth fall-to-spring. Regardless, standard 6 mil poly film needs to be replaced every three to five years in many locations. While many growers may not give the film that covers their high tunnels much thought, it is usually the only thing that separates their crops from the outside and it influences their success in many obvious and not so obvious ways. Therefore, it is reasonable for growers to seek and expect improved high tunnel coverings just as they expect better versions of all other materials used on the farm.
We are pleased to be cooperating with the Seaman Corporation of Wooster, Ohio (https://www.seamancorp.com/), long known as an industry leader in high performance industrial fabrics. Together, we are evaluating the company’s exciting new experimental reinforced poly film which is far stronger and more puncture and tear resistant than standard 6 mil poly film and has other interesting properties that may, for example, allow it to supplement or replace hard polycarbonate in some applications.
As depicted below, HT 103 on the CFAES-Wooster campus currently contains a crop of butternut squash and was covered with the new film on 8/12/24. HT 204 is about 100 ft east of HT 103, identical in shape and age, covered with standard 6 mil poly film, and holding butternut squash. Going forward, cropping, ventilation, and other practices will be the same and environmental conditions will be monitored in both high tunnels. Therefore, overall, differences in environmental conditions and/or crop status in the two high tunnels are likely to result from their different coverings. Monitor temperature and relative humidity in high tunnels 103 and 204 and six other structures at the same location at https://u.osu.edu/vegprolab/resource-1/ and stay tuned for updates on this important evaluation.
Crop selection and soil management and long-term soil productivity are interconnected. Many high tunnel soils are:
a) cropped repeatedly to relatively small sets of input-demanding crops,
b) disturbed frequently and intensely by cultivation and preparing for seeding and transplanting, and
c) exposed to persistent foot and equipment traffic.
High tunnel soils also tend to experience potentially troublesome temperature and moisture profiles. As a result, high tunnel soils can:
a) lose structure and become less friable and more compacted,
b) decline in organic matter,
c) increase in salinity, and
d) develop problematic nutrient imbalances and pathogen loads.
These and other challenges can lead high tunnel soils to become less productive – to require greater and greater amounts of cash and effort to maintain marketable yields at desired levels.
Including additional, less demanding cash and non-cash rotation or cover crops in high tunnel production schedules can help maintain soil productivity and offer other benefits.
Five 21 ft x 48 ft high tunnels used intensively in organic vegetable production-related research for 15-21 years are currently being cropped to butternut squash or a mixed-species summer cover crop (cowpea, Italian ryegrass, pearl millet, and sorghum-sudangrass). See representative panels below. The mixed-species cover crop has produced significant amounts of foliar biomass and suppressed weed growth effectively. Its root system is expected to provide multiple benefits. Similarly, squash plant growth and flower production have been excellent and fruit set is encouraging. Nine-hundred pounds of composted dairy manure were spread in each high tunnel on 4/16/24 and lightly incorporated but no fertilizer or crop protectants have been applied since. Both crops have been overhead irrigated (see https://u.osu.edu/vegprolab/crop-environment-publications/installing-an-overhead-irrigation-system-in-a-high-tunnel/).
Sections of other nearby high tunnels have been planted to buckwheat, carrot, Swiss chard, choi, dry bean, edamame soybean, garlic, groundpea (winter cover), kale, lettuce, okra, pepper, sunflower, and/or wheat (winter cover) since October-2023.
Cash crops can be harvested from high tunnels year-round in Ohio. Maintaining the productivity of soils that help make that possible is key. Considering what many cash and non-cash crops can offer to the process is useful.
Following initial detection in Medina County the first week of July, additional confirmations of this pathogen have been made from fields in Wayne, Seneca, and Huron counties, as well as the OSU Extension seminal plot in Wooster. Laboratory diagnosis was conducted by the C. Wayne Ellett Plant and Pest Diagnostic Clinic at the OSU CFAES Wooster Campus. Monitoring continues at OSU sentinel plots in Fremont, Celeryville, and Piketon, with no confirmed detections at the time of writing. Additionally, symptoms consistent with bacterial spot, yellow-vine decline, and bacterial wilt have been observed in the sentinel and nearby plots at OSU research stations across the state, so diligence in insect and disease scouting and management remains imperative.
Heavy sporulation on the underside of a cucumber leaf in Wayne county Sentinel plot F. Rotondo.
Visual foliar symptoms on the upper surface of cucumber leaves from Huron (left) and Wayne (right) counties, F. Rotondo
Microscope view of Cucurbit Downy Mildew, where the individual, lemon-shaped, sporangia can be observed along with sporangiophores, F. Rotondo.
The following information appeared in this newsletter on July 2nd but remains relevant and is reposted for reader convenience.
Growers who have cucumbers and cantaloupe in their fields should take quick action to protect their crop. Cucurbit Downy Mildew is best managed with preventative applications before infection takes place. Once visual symptoms appear, control becomes increasingly difficult and yield reductions may occur. In conditions favorable for disease development, and without effective and timely management, Cucurbit Downy Mildew can cause rapid decline of the plant, severe defoliation and ultimately plant death in just the matter of days. Disease development is favored by rainy, humid conditions (relative humidity greater than 85%) and cooler temperatures ( 60°F to 70°F)
According to research trials completed in Ohio, Michigan, and other states and provinces around the Great Lakes region, the best fungicide options are as follows: Orondis Opti (FRAC 49+M05), Ranman (FRAC 21), Omega (FRAC 29), Previcur Flex (FRAC 28), and Elumin (FRAC 22). These should be tank mixed with chlorothalanil (Bravo, Equus, etc.) or mancozeb (Dithane, Manzate, etc.). Orondis Opti is a premix already containing chlorothalanil, but at a reduced rate. Fungicides have restrictions on how much product can be applied and how often, so follow the label, the label is the law. The more effective fungicides should be rotated to avoid resistance development in the pathogen.
Growers in Ohio should also intensify scouting of cucumbers and melons. Look for yellow or tan angular lesions delimited by veins on the top surface of leaves, and fuzzy grey/brown growth on the undersides of the lesions. With a good hand lens or a smartphone camera with high magnification you may be able to see small dark brown/purple spots within the fuzzy growth. These are the spores of the downy mildew pathogen. You can also utilize the Cucurbit Downy Mildew IPM Pipeline website, where you can sign up for alerts notifying you of nearby confirmed Cucurbit Downy Mildew observations.
If you suspect downy mildew in cucumber or melon please submit samples to the C. Wayne Ellett Plant and Pest Diagnostic Clinic (CWE-PPDC) for confirmation. Instructions for sample submission are here. Please contact Dr. Francesca Rotondo at 330-263-3721 or rotondo.11@osu.edu with any questions. You can also work with your county extension educator to get samples submitted to the lab. A major ‘thank you’ to Dr. Rotondo and her staff in the Plant and Pest Diagnostic Clinic for their critically important work! Also, thanks to financial support from the Ohio Produce Growers and Marketers Association’s Ohio Vegetable and Small Fruit Research and Development Program, there is no fee for this service for Ohio vegetable growers. Please find additional information on Cucurbit Downy Mildew here from OSU and Michigan State
