Month: July 2021

Wayne County IPM Notes from the Week of July 12th – July 16th

Vegetable Crops

Of most importance, the Vegetable Pathology Lab in Wooster confirmed Downy Mildew on a cucumber plot at OARDC. Cucumber growers are highly encouraged to begin taking action to protect their plants, especially as more cases are confirmed around the area.

Squash vine borer on a pumpkin plant. Tommy Becker photo.

Japanese beetles are out in force this year and continue to be one of the most consistent insect pests from week to week on a wide range of crops. Other insect pests of note included Colorado Potato Beetles that have migrated off of harvested potato plantings in into tomato and eggplant plantings. In squash, we have still been finding quite a few squash bug egg masses. Squash Vine Borers have also been spotted in some area pumpkin plantings.

Colorado Potato Beetles feeding on a tomato plant. Tommy Becker photo.

During these heavy rains, we have noticed a significant amount of soil splashed up onto the plants and fruit. This will likely encourage more disease incidence. Accordingly, take extra time and care to scout your crops in the coming weeks.

Sweet corn pests like corn ear worm and European corn borer are not showing much activity in our traps. We occasionally find damaged tassels from ECB feeding, however, we have yet to have any fields go over the 10% damage threshold.

Small Fruit and Orchards

 Between last week and this week, we have seen a sustained flight of oriental fruit moth in area peach blocks as our traps have been well over threshold for the last two weeks. Our codling moth traps still do not show much activity.

Over ripe Lodi apple that had spilt following a heavy rain.

We did find some interesting things while scouting apples this week, including blister spot on some “Delicious” apple varieties and Lodi apples that had burst and fell off the trees due to being over ripe.

As a note for all small fruit growers, all of our traps for SWD in the area are currently catching SWD, therefore, we recommend you treat your small fruit. Pay close attention to the label, especially the REI (re-entry interval) and PHI (pre-harvest interval). Another note for all fruit crops, Japanese beetles are feeding on grapes, apples, peaches, and blueberries. The beetles can do significant defoliation as well as damage to the fruit.

Cucumber Downy Mildew Confirmed in Northern Ohio

Cucurbit downy mildew occurrences in the eastern US. https://cdm.ipmpipe.org.

Downy mildew was reported on pickling cucumbers in Seneca County today. The field was heavily damaged, with about 90% of the plants showing symptoms. We also found one confirmed downy mildew lesion in our sentinel plot in Wooster (Wayne County). These are the first reports for 2021 of cucurbit downy mildew in Ohio, following an outbreak in Chatham-Kent, Ontario reported on June 17. Growers in northern Ohio should protect cucumbers  and melons with effective downy mildew fungicides such as Orondis Opti, Ranman, Omega, Elumin, Previcur Flex or Zing!. Remember to alternate products in different FRAC groups and tank mix with a chlorothalanil product or other protectant fungicide – except for Zing!, which contains chlorothalanil in the premix.  Check the labels carefully for use instructions and restrictions. Fungicides must  be applied preventatively – they  are far less effective if applied after  infection.

Growers in central Ohio should intensify scouting of cucumbers and melons and apply a protectant fungicide. 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.

Smartphone image of a downy mildew lesion with the pathogen sporulating on the underside of a cucumber leaf.

If you suspect downy mildew in cucumber or melon please text or email pictures to Sally Miller (330-466-5249; miller.769@osu.edu) of both sides of lesions, with the underside in the highest possible magnification. I can often confirm downy mildew from photos, but if not will ask you to send a sample to the OSU Vegetable Disease Diagnostic Lab for confirmation. Instructions for sample submission are here. 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.

Wayne County IPM Notes for the Week of July 5 – July 9

Vegetable Crops

High tunnel tomatoes were one of the areas of focus for disease development this past week. Many high tunnel tomatoes are currently experiencing cases of leaf mold. As a side note on high tunnel tomatoes, we did observe a thrips outbreak in a high tunnel, where heavy feeding by the thrips was causing significant discoloration of the foliage and stunting of the plants. Peppers took the other majority of the focus with disease development, mainly due to favorable conditions for bacterial diseases to manifest. Several pepper samples tested positive for bacterial infection.

Flea beetles seemed to make a comeback this week. Several fields of cole crops were over threshold for flea beetle counts. Japanese beetles are continuing to feed in the majority of the crops planted in the area. Other insects like squash bugs are starting to be found more frequently, specifically in early planted summer squash.

Sticking with cucurbits, we are starting to find spots of powdery mildew in plantings of zucchini and yellow squash. It is important to scout your crops and look for powdery mildew, especially if you have succession plantings of young cucurbit crops nearby. Powdery mildew is easily spread onto younger plants, so it is recommended that you keep up with spraying for powdery mildew and terminate the older infected plantings once you are done harvesting.

Small Fruit and Orchards

 First and foremost, we have found spotted winged drosophila in the Wayne County area. The threshold for SWD in small fruit is 1 fly. Since we are now finding adults, we encourage growers to also do salt tests on the berries to check for larvae.

Wooly apple aphids continue to show up in the several apple orchards in the area. These are a tough pest to get under control due to their protective waxy coating.

OFM counts in some peach blocks were above threshold for the first time in several weeks. OFM counts remained well below threshold.

Syncing the Amount of Water Available to Crops with Their Need for It

Vegetable growers work to ensure their crops have the water they need, but only the amount they need, from crop initiation through harvest. It’s a big, complex job requiring attention to water supply and demand, including soils and crops, and much preparation because the time to verify that drainage and irrigation capacities are adequate is before they are needed.

Indeed, when rainfall is excessive, the combined abilities of the soil and drainage system to accommodate the load is key, along with the crop’s ability to withstand flooding. Mapping fields soon after a “flooding rain” or lengthy irrigation cycle can identify where drainage improvements may be essential. Such improvements often result from combinations of “plumbing” (e.g., tiling), soil management and additives, and rethinking (lengthening and diversifying) crop rotations. If water is entering the high tunnel from outside it, grading the site may be necessary.

Irrigation is applied when there is clear evidence soil moisture is below crop need. Verifying the irrigation system is up to the task and knowing when to turn the system on and off are three critical tasks and decisions.

Whether overhead or drip, each irrigation system can deliver a specific amount of water in a fixed amount of time. However, using flow meters and periodically checking the condition of the system helps verify the flow rate to the crop is truly equal to the system’s calculated capacity. Leaks and blockages interfere with delivering the desired amount of water throughout the field or planting.

Knowing when and for how long to run the irrigation system requires clear and reliable reads on both the crop’s need for water and its availability from the soil. Years of farming experience and a strong understanding of soil conditions and irrigation systems are obvious assets in making those assessments. However, off-the-shelf technology (e.g., soil probes, tensiometers, gypsum blocks, flow meters) and decision aids (e.g., crop evapotranspiration calculators, irrigation charts in production guides) complement experience and reduce the irrigation learning curve. Irrigate to meet crop need and avoid under- or overshooting it significantly as often as possible.

Another point about crop water needs which affect the timing and/or amount of irrigation: they vary meaningfully with multiple crop-based, abiotic, and grower-based factors.

Two related ones may be critical at this point in the season many have experienced to date. First, alternating dry-wet periods have made it difficult for some to maintain soil moisture at levels consistently equal to crop need. For example, some have asked how much to credit rainfall under a variety of circumstances, including when plastic-covered raised beds are used. Moisture sensors under the plastic would be useful in making that determination. Second, soil conditions and irrigation practices can shape root systems which, in turn, influences the crop’s ability to take-up water. Overall, excess soil moisture, including because irrigation has been excessive, can result in shallow root systems. Shallow root systems limit plant access to water, making the crop more prone to displaying symptoms of low water stress although moisture levels deeper in the soil profile may be adequate. Wilting or other symptoms trigger irrigation, continuing the cycle. So, while it is never clear beforehand if the season will be dry, wet, or just right, the best practice is to irrigate according to crop need from the start and to rigorously cross-check assessments of crop need against the best-available information.

Addendum: More Powdery Mildew Fungicides for Cucurbits

Thanks to Jim Jasinski for providing more info on fungicides for powdery mildew that he has tested on cucurbits. The following table is amended from my post on July 6, 2021 to include three additional effective fungicides: Miravis Prime, Luna Experience and Luna Sensation. Please read the July 6 post for more details on how and when to use these products.

It’s time to talk noxious weed laws…

Poison hemlock and Canada thistle are making unwelcome appearances across Ohio, and that raises the need to talk about Ohio’s noxious weeds law.  The law provides mechanisms for dealing with noxious weeds—those weeds that can cause harm to humans, animals, and ecosystems.  Location matters when we talk about noxious weeds.  That’s because Ohio law provides different procedures for dealing with noxious weeds depending upon where we find the weeds.  The law addresses managing the weeds on Ohio’s noxious weeds list in these four locations:

  1. Along roadways and railroads
  2. Along partition fence rows
  3. On private land beyond the fence row
  4. On parklands

Read more here

Veterans Harvest: A Virtual Conference for Veterans in Agriculture

5 consecutive Tuesdays beginning July 27, 2021    1:00 – 2:30 p.m. ET

The National AgrAbility Project is pleased to present Veterans Harvest: A Virtual Conference for Veterans in Agriculture.

Click here for the registration form. All sessions are free. Those already registered for the 2021 AgrAbility National Training Workshop Virtual Sessions are automatically registered for the veterans’ conference. Register by Thursday, July 22. Instructions for accessing the session will be sent to registrants by Monday, July 26.

The current conference agenda includes the following sessions:

  • July 27: “Conference Introduction” by Cindy Chastain, National AgrAbility Project, and Jeanette Lombardo, Farmer Veteran Coalition, plus “One Veteran’s Journey from PTSD to Farmer” by Sarah Creech, Blue Yonder Organic Farm and Indiana Farmer Veteran Coalition
  • August 3: “Celebrating Veteran Total Farmer Health” by Linda Emanuel and Shay Foulk, AgriSafe Network
  • August 10: “Programming for Veterans in Agriculture: How Maine Does It” by Anne Devin, veteran outreach specialist with Maine AgrAbility
  • August 17: “Update on USDA’s support for Veterans” by Bill Ashton, USDA Military Veterans Agricultural Liaison
  • August 24: “Panel Presentation on State/Regional Programs for Farmer Veterans” moderated by Cindy Chastain, National AgrAbility Project

“Agriculture has become an important source of employment and healing for many veterans,” says Cindy Chastain, National AgrAbility’s veteran outreach coordinator. “A large percentage of veterans come from rural areas, even though not all of them grew up on farms. After leaving the military, they discover that working in agriculture fulfills them in ways that other occupations can’t.”

Groups involved with the conference include Farmer Veteran Coalition (FVC) and Indiana AgVets. FVC is a national organization with chapters in Indiana and 23 other states that helps veterans develop viable employment and meaningful careers through the collaboration of the farming and military communities. Indiana AgVets is a USDA-sponsored agricultural career training program, led by Hoosier Uplands Economic Development Corporation in cooperation with Purdue’s Indiana AgrAbility Project, which provides internships and other support for U.S. military veterans in Indiana or surrounding states.

Please pass on this invitation to others you believe may be interested. Contact AgrAbility at 800-825-4264 or email agrability@agrability.org if you have questions.

The National AgrAbility Project is supported by USDA/NIFA Special Project 2016-41590-25880.

Managing Mildews in Home Garden Cucurbits

Downy mildew of cucumber.

Downy mildew and powdery mildew are very different diseases of cucurbits but they  have in common that they are obligate pathogens that require a living plant for survival and thus don’t overwinter in Ohio. Downy mildew appears from late June to August in northern Ohio (but not observed yet!) and August to September for central  and southern Ohio. Powdery mildew appears without fail in the first half of July throughout Ohio. Both mildews are managed by resistant varieties when available and fungicides. For gardeners, fungicide options are limited.  For downy mildew the best option is a chlorothalanil product applied preventatively. You  can follow me on Twitter @OhioVeggieDoc for alerts on downy mildew appearance in Ohio, or check this blog or the national cucurbit downy mildew forecasting site: https://cdm.ipmpipe.org.

Advanced powdery mildew on pumpkin.

Powdery mildew will show up on pumpkins and other cucurbits soon if not already here. Fungicides should be applied as soon as powdery mildew is observed. Sulfur products are most effective of those listed. Potassium bicarbonate and Serenade Garden also have some efficacy against powdery mildew.  Note these are all protectants and only work on the leaf surface. Therefore full coverage is needed throughout the canopy (top and bottom of leaves, petioles).

Cucurbit Powdery Mildew Management Recommendations

Powdery mildew colonies on upper leaf surface.

Powdery mildew normally appears on pumpkins and other cucurbits in Ohio in early July. Signs of infection are small circular powdery growths on either side of the leaf. These spots enlarge and can eventually cover most of the leaf surface and kill the leaves. Stems and leaf petioles are also susceptible, but the disease is not observed on fruit. In pumpkins, powdery mildew may also attack the “handles”, which can be further damaged by secondary pathogens. It is time to start scouting cucurbits for powdery mildew.

Powdery mildew is managed using disease-resistant varieties and fungicides. Pumpkin and squash varieties vary in resistance to powdery mildew; in general, the more susceptible the variety, the more fungicide needed. The choice of fungicide is important because insensitivity to overused fungicides is common. It is critical that a fungicide resistance management

Powdery mildew colonies on lower leaf surface.

program is followed. Alternate fungicides in different FRAC (Fungicide Resistance Action Committee) groups, indicating different modes of action against the fungus. Fungicide applications should begin when the disease first appears and incidence is low. Fungicides that are labeled for use against cucurbit powdery mildew can be found in the Midwest Vegetable Production Guide for Commercial Growers; product ratings and FRAC codes are on page 11.

Our evaluations of efficacy of powdery mildew fungicides in Ohio in 2020 indicated that Aprovia Top, Inspire Super, Gatten, Vivando and Procure provided very good control of powdery mildew on pumpkins (see table below).  Microthiol Disperss was not tested in 2020 but historically has provided good control. Quintec and Fontelis provided moderate (53-65%) control and Bravo Weather Stik, Merivon Xemium,  Pristine, Torino and Rally provided poor control. The bioassay full report can be found here (pp. 15-16).

A list of products for powdery mildew management in organic cucurbits prepared by Dr. Meg McGrath of Cornell University can be found here.

 

Insect Monitoring Network Highlights – July 3rd

As in prior years, Ohio State University has a network of traps set across the state to monitor key fruit and vegetable pests to help growers better manage these pests. These traps are checked weekly by state specialists, extension educators and some growers. Funding for the network comes from the OSU Extension IPM Program.

The trap data can be accessed here:
https://docs.google.com/spreadsheets/d/1KLU8rEoaz1Cnt9ILbUf77tSxOIriwZR0Xtj-wwNZgDA/edit?usp=sharing

Based on those cooperators who have reported numbers to date, here are some highlights to be aware of:

Spotted wing Drosophila are being detected in Brown, Greene and Geauga counties, so growers who have ripening or ripe small fruit (blueberries, raspberries, blackberries or strawberries), peaches or grapes, should be monitoring and ready to treat if just one SWD is detected. Treat through harvest to protect berries. More biology and treatment details can be found here: https://u.osu.edu/pestmanagement/pests/swd/

Corn earworm is a pest of several crops but is particularly attracted to silking sweet corn. Increasing CEW have been trapped in Clark, Sandusky, Seneca, Wayne and Putnam counties. The chart below provides a treatment schedule based on the number of moths and the peak temperature.

Corn earworm management chart.

European corn borer, another pest of sweet corn and peppers, has been detected in a few counties (Clark, Sandusky, Seneca and Wayne) but the numbers seem relatively low as the first generation of moths is declining.

 

Squash vine borer adult on pumpkin leaf.

For growers of cucurbit crops (pumpkin, squash, melons) there has been an upswing in Squash Vine Borer moths detected in Clark, Greene, Putnam and Lucas counties. If growers decide to treat, aim for the base of the plant and be aware of application restrictions if plants are flowering (for pollinator safety).

 

 

A few Spotted Lanternfly nymphs have been caught in circle traps around Mingo Junction in Jefferson county where they were first seen last year. Catching them in traps at this location was expected and ODA has plans to treat that area to prevent the spread. Remain vigilant for late instar nymphs which are red, black and white; soon to follow will be the adults which are capable of flight.

Erika Lyon’s photo of SLF nymph caught in trap.

3D printed Spotted Lanternfly (early nymph, late stage nymph, adult).