Scouting Notes From the Wayne County IPM Program

Here are our weekly observations and notes from the fields around Wayne County from the week of June 20-24, 2022.

Vegetable Crops

Now is a critical time to be monitoring your cucurbit crops for cucumber beetles. Early populations may not seem as evident due to the presence of insecticide in treated seed, however, as the efficacy of the seed treatment diminishes, the cucumber beetle feeding will begin to increase. The threshold for beetles while the plants are in the 2-4 leaf stage is 1 beetle per plant. Once the plant is above the 4-leaf stage, the threshold increases to 3 beetles per plant. The greatest chance for impactful feeding damage and bacterial wilt infection via the cucumber beetle occurs during early season feeding.

Squash bug found in Wayne County on yellow squash. Cucumber beetles feeding in the background. F. Becker, 2022.

Also, of note in cucurbits, the excess moisture and warm conditions allowed for development of some phytophthora cases. If you suspect that you have plants infected by this pathogen, avoid spreading it in your fields by removing and destroying infected fruit and plant material. An integrated approach to managing this disease includes practices such as avoiding excess water, sufficient crop rotations and fungicide treated seed. Additional findings in cucurbits included squash bugs being found this week in an early planting of yellow squash.

An area of yellow squash plants lost due to phytophthora, F. Becker, 2022.

Continue to monitor onions for thrips populations. The recent heavy rain may have prevented populations from building, however, hot dry weather, combined with the increased size and number of leaves can provide the opportunity for thrips numbers to escalate rapidly.

In tomatoes our scouts noted some observations of early blight and Septoria.

Remember to check your crops for any signs of foliar diseases, especially with the amount of soil splashing that took place in the last few weeks. Bacterial and fungal diseases can be spread on the lower leaves of plants when heavy rains splash soil and pathogens onto the foliage. Overall, stress from high temperatures has been evident in a majority of the crops that we are scouting.

Small Fruit and Orchards

Male SWD, Thomas Becker photo, 2022

Female SWD, Thomas Becker photo, 2022.

Spotted winged drosophila have been caught in traps around Wayne County. As we move out of strawberry season into raspberries/blackberries/blueberries, the SWD populations will begin to increase leading to possible infestations in ripening brambles and blueberries.

In apples, we continued to find strikes of fire blight. Conditions have been ideal for fire blight development, although dryer conditions may hinder further development. This week we continued to find aphids in apple trees. Our IPM program identified populations of green apple aphids in several orchards as well as a case of wooly apple aphids. Both aphid species can cause significant damage at this time of year. Accordingly, diligent scouting is a crucial aspect to not allowing either of these aphid species from getting out of hand. The heavy rains likely knocked back some of these aphid populations, but it will be important to monitor aphid populations as dry conditions take hold.

We have had sustained catches (over threshold) of both Codling Moth and Oriental Fruit Moth in apple and peach orchards, respectively. Over the last week, both Codling Moth and Oriental Fruit Moth populations have been trending downward, however, numbers have still exceeded the thresholds.

Now is the time to be managing early season diseases in apples. Scab, rust and powdery mildew are the three main diseases of concern at this point in the season.

Once strawberry harvest is over, it is a good time to consider renovation of the patch. The goals in renovation are to reduce plant numbers by narrowing the rows, remove old foliage (reduces diseases), control weeds, and reduce insect pests. After renovation, regular irrigation and weed control are essential. High yields next year depend on having large, healthy, vigorous plants when fruit buds are initiated in late summer.

We have started catching grape berry moth in our traps.

Preparing for Cucurbit Powdery Mildew

Powdery mildew colonies on the underside of a pumpkin leaf. Fungicide applications should start when these colonies are first observed during scouting. It is important to check both surfaces of the leaves. Photo by Josh Amrhein.

Powdery mildew usually appears on pumpkins and other cucurbits in Ohio beginning in early July. The pathogen does not overwinter in Ohio; infections result from spores blown into the area on the wind.  Powdery mildew is favored by moderate to high temperatures and high humidity. However, unlike most other fungal plant pathogens, it is inhibited by free moisture on the leaf surface.

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 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 searchable Midwest Vegetable Production Guide for Commercial Growers.

OSU evaluations of efficacy of powdery mildew fungicides in Ohio in 2021 indicated that Aprovia Top, Luna Experience, Inspire Super, Rally, Miravis Prime, Luna Sensation, Microthiol Disperss, Vivando and Procure provided very good control of powdery mildew on pumpkins (see table below).  Velum Prime, Cevya, Prolivo and Gatten provided good control of powdery mildew on upper leaf surfaces but poor control on the lower surfaces.

Quintec provided good control in 2021 but in other years and other states has failed due to resistance. Fontelis, Bravo Weather Stik, Merivon Xemium, Pristine, and Torino have been shown to provide poor or variable control in Ohio or other states and are not recommended.

Always check label for full list of allowed crops and use recommendations and restrictions.

2021 OSU Vegetable Disease Management and Diagnostics Reports Now Available

Alternaria leaf spot on cabbage

The OSU Vegetable Pathology Lab carried out an active field research program in 2021, with ten full field trials spread across three research sites in Wooster, Celeryville and Fremont, OH, and three bioassays for downy and powdery mildew management. We tested fungicides, biological control products, and disease-resistant varieties to manage diseases of tomatoes, peppers, cucumbers, pumpkins, cabbage and collards. Our vegetable disease diagnostic lab service for commercial growers, led by Dr. Francesca Rotondo, diagnosed 241 physical samples and 20 digital samples for Ohio growers at no cost. You can click here Plant Pathology Series 2022_Veg Pathology Research Rpts 2021_final to read the research trial and diagnostic lab reports. Most of these trial results will be published in 2022 in Plant Disease Management Reports (subscription required).

Research projects (those with an * were supported financially by the Ohio Small Fruit and Vegetable Research and Development Program):

*Tomato anthracnose – fungicide evaluation

Tomato black mold, Septoria leaf spot and anthracnose – fungicide evaluation

Pepper bacterial canker – evaluation of cultivar resistance

Pepper Pseudomonas leaf spot – evaluation of cultivar resistance

*Pepper anthracnose – fungicide evaluation

Cucumber downy mildew – evaluation of cultivar resistance

Cucumber downy mildew – fungicide resistance screening (bioassay)

*Pumpkin powdery mildew and Plectosporium blight – fungicide evaluation

*Pumpkin powdery mildew – fungicide resistance screening (bioassay)

*Pumpkin powdery mildew – OMRI-listed products evaluation (bioassay)

Cabbage Alternaria leaf spot and soft rot – fungicide and biological product evaluation

Cabbage white mold – fungicide and biological product evaluation

Collards black rot and peppery leaf spot- biological product testing

*Vegetable disease diagnostic report

Phytophthora Blight on Pumpkin Fruits

Phytophthora blight on pumpkins received in October 2021 by the OSU Plant Disease Diagnostic Lab in Wooster. Photo by Francesca Rotondo.

This has been a rainy growing season in much of Ohio and other states east of the Mississippi River. With intense rain events leading to standing water in fields and stretches of hot weather, both favorable for Phytophthora capsici, the cause of Phytophthora blight, the disease has been such a problem that shortages of jack-o-lantern as well as pie pumpkins are expected this Fall.  If Phytophthora blight was detected in a field at any time this season, growers are advised to harvest mature, uninfected fruits as early as possible.  These fruits need to be laid out individually (not touching, so bins are not acceptable) in a shaded area with good ventilation so that they can cure.  A barn floor would be an ideal location since they would not get rained on, but outside under a tree (to prevent sunscald) would be better than nothing.  If putting them outside, do NOT put them on a tarp or plastic that would tend to hold rainwater and spread the disease to the other fruits.  If any of these fruits start to show signs of infection (discolored areas or white, cottony growth – see photo) remove them from the area immediately and discard them in an area away from the fields or curing location.

Dr. Meg McGrath of Cornell University found that hosing pumpkins off first to remove soil (using a garden hose with a trigger spray nozzle) was the second most important step in reducing disease incidence (getting them out of the field being the most important).  Washed fruits need to be dried as quickly as possible. Dipping fruit in 10% Clorox, GreenShield or Kocide was no better than just hosing them off, and these products are not labeled for this use.

Pumpkins (or other cucurbits) with symptoms in the field should be removed and destroyed away from the field and surface water sources. Leaving them in the field will contribute to inoculum buildup; if Phytophthora blight was present in a field, practice rotation of at least four years away from susceptible crops including all cucurbits, peppers, tomatoes, and beans.

Ron Becker contributed to an earlier version of this post in 2007. We thank the Ohio Produce Growers and Marketers Association’s Ohio Vegetable and Small Fruit Research and Development Program for financial support of our disease diagnostics program.

 

 

New Reports of Downy Mildew on Pumpkins and Cucumbers in Ohio

Downy mildew symptoms on untreated pumpkin leaves in Clark County, OH. Photo by Jim Jasinski.

Downy mildew was reported for the first time in pumpkins in Ohio in Clark County at the OSU Western Agricultural Research Station. Jim Jasinski noticed possible symptoms in an untreated control in a pumpkin research trial as many as 10 days ago, but the disease did not progress rapidly in last week’s heat. However, we were able to confirm downy mildew today. This is so far the furthest north that downy mildew has been found and reported on pumpkins or squash in the US. It is likely caused by Clade 1 of the pathogen, which comes from SE US and is more aggressive on pumpkins, squash and watermelons than other cucurbits.  Pumpkin and squash growers throughout Ohio should apply appropriate protectant fungicides now and scout fields thoroughly. Growers in Clark County should begin a fungicide program with downy mildew-effective fungicides now.

In the last week or so Ohio Master Gardener Volunteers in our Citizen Science project to monitor this disease have also reported downy mildew on cucumbers in Belmont, Jefferson and Geauga counties. Rainy or cloudy weather and moderate temperatures are expected this week in much of Ohio – these conditions are ideal for downy mildew.

For all cucurbits: If favorable conditions for downy mildew persist and downy mildew is present in your area, add effective fungicides shown in green in the Table to the spray program. Tank mix with a protectant fungicide, alternate fungicides with different modes of action (FRAC codes) and follow the label restrictions and requirements. Shorten the application interval to 7 days under favorable weather for downy mildew.

  1. Forum, Presidio, Quadris, Zampro and Revus are not recommended. Curzate may be moderately effective in some locations.
  2. Follow this blog, Twitter @OhioVeggieDoc or the Cucurbit Downy Mildew IPM PIPE for downy mildew reports.

Map of US counties with cucurbit downy mildew reports. https://cdm.ipmpipe.org/

Wayne County IPM Notes From August 9 – 13

Vegetable Crops

Squash vine borer damaged plants.

This week brought about many sightings of squash vine borer larva. The adult squash vine borer moths were actively flying and lay eggs about a month ago. We are now seeing plants that are declining in health and when inspected further, are oozing frass and have stems that look shredded. When we split the stem of these plants, in nearly every instance, we found at least one, if not several squash vine borer larvae. Unfortunately, there is nothing that can be done to reverse such severe damage.

A large squash vine borer found feeding in a pumpkin plant.

Flea beetles are feeding on young cabbage and broccoli, and the cabbage worm butterflies are finding their way into these plantings as well. We are starting to see some damage in peppers from the European corn borer and expect the ECB and CEW numbers in the traps to increase in the next week or so.

Small Fruit and Orchards

As apples and peaches are harvested, do not let your guard down on the late season generations of codling moth and oriental fruit moth. This past week was another week of rising codling moth numbers, and consistent oriental fruit moth catches, although the oriental fruit moth numbers have not gone back over threshold.

Grapes damaged by grape berry moth larvae.

Grapes are starting to ripen, and as the season progresses, we are still finding consistent trap catches of grape berry moth. Although it may be too late for some varieties, you may still be able to protect later maturing varieties with a treatment for grape berry moth.

Cucurbit Downy Mildew Outbreaks Increasing

Cucurbit downy mildew outbreak map. https://cdm.ipmpipe.org.

We have three new reports of downy mildew on cucumbers this week, all from home or community gardens in Coshocton, Muskingum and Geauga counties. Thanks to OSU Extension educators David Marrison and Clifton Martin for the finds in Coshocton and Muskingum counties. The Geauga County outbreak was reported by one of our Ohio Master Gardener Volunteers participating in a multi-state Citizen Science project to monitor and report cucurbit downy mildew (thanks Annie!). Numerous reports in other states show that downy mildew is on the move (see map), mostly still in cucumbers and melons. In Ohio the cucumber/melon outbreaks have been in the northern and central counties, likely caused by the downy mildew “pathotype” that circulates in the Great Lakes region and infects only cucumbers and melons. However, last week downy mildew was reported on squash and pumpkins in Central Kentucky and on squash in Western New York. The downy mildew “pathotype” that infects squash and other cucurbits moves up into the Midwest from the deep South, so Ohio growers, especially in the southern counties, should step up scouting of all cucurbits and apply protectant fungicides such as chlorothalanil products. When downy mildew is confirmed nearby and conditions are conducive (cool, rainy, humid, overcast), more effective fungicides should be applied.

Spray Program Recommendations for Ohio Cucurbit Growers

  1. Northern and Central Ohio cucumber and melon growers: add effective fungicides shown in green in the table to the spray program now. Tank mix with a protectant fungicide such as chlorothalanil (Bravo, Equus, etc.), alternate fungicides with different modes of action (FRAC codes) and follow the label restrictions and requirements. Shorten the application interval to 7 days under favorable weather for downy mildew.
  2. Southern and Central Ohio cucurbit growers (all types): apply a protectant fungicide on a 7-10 day schedule now.

If favorable conditions for downy mildew persist and downy mildew is present in your area, add effective fungicides shown in green in Table 3 to the spray program. Tank mix with a protectant fungicide, alternate fungicides with different modes of action (FRAC codes) and follow the label restrictions and requirements. Shorten the application interval to 7 days under favorable weather for downy mildew.

  1. Forum, Presidio, Quadris, Zampro and Revus are not recommended. Curzate may be moderately effective in some locations.
  2. Follow this blog, Twitter @OhioVeggieDoc or the Cucurbit Downy Mildew IPM PIPE for downy mildew reports.

Click to enlarge.

Wayne County IPM Notes from July 19 – 23

Vegetable Crops

Powdery mildew found on a cucurbit plant in a Wayne County field.

The Vegetable Pathology Lab at OARDC has confirmed several more cases of downy mildew, on both cucumbers and cantaloupe. It is important to take steps to either protect your crop or stop the spread of any ongoing infections. Powdery mildew is also spreading rapidly through the area. Although some heavy rains may have slowed its spread, favorable conditions have led to some fields rapidly becoming infected.

Flea beetles feeding on young green cabbage plants.

Bacterial diseases continue to spread in pepper and tomato plantings. Pay close attention to these crops in particular, and make sure that you are taking the necessary precautions so as to not spread bacterial diseases. Bacteria can be spread from plant to plant via clothing, equipment, or animals. More from APS

Flea beetles are feeding heavily on recently planted cole crops, which left uncontrolled can cause stunted and underperforming plants. Another insect we have seen quite a few of is the squash vine borer. Although these are not typically going to harm large numbers of plants, they can still be a nuisance, especially in smaller plantings.

Small Fruit and Orchards

 This week we found our first incidence of scab in apples. While this was only an isolated find on a few leaves, it is a good reminder to take some time to scout your apple trees and look for any signs of scab. Oriental fruit moth numbers were significantly above threshold again this week. Japanese beetles were also

Severe damage from Japanese beetles feeding on the foliage of apple trees.

still feeding heavily in many of the fruit crops we scout. Spotted wing drosophila are still being found in all of our traps, and for anyone with small fruit in the area, it is recommended that you treat for SWD.

Cucurbit Downy Mildew Continues to Spread in Northern Ohio

Downy mildew map. https://cdm.ipmpipe.org

After last week’s very wet weather, downy mildew has appeared on cucumbers in a research plot on the OSU Muck Crops Research Station (Huron County) and on cucumbers and melons in sentinel plots on the OSU CFAES Wooster campus (Wayne County) and the OSU North Central Agricultural Research Station in Fremont (Sandusky County). In addition, downy mildew continues to spread in commercial fields in Seneca County. Downy mildew is likely to be present in cucumbers and/or melons in other northwest and northcentral Ohio counties and growers should protect these crops with appropriate fungicides. Fungicides must be applied preventatively – once plants are infected they will show symptoms within ~5-7 days even if fungicides are applied after infection. Only the fungicide Curzate has moderate “kick-back” activity.

OSU is part of a multi-state cucurbit downy mildew monitoring project, for which this year we have enlisted the help of Master Gardener Volunteers (MGVs) as Citizen Scientists in counties throughout Ohio. Most (25) are monitoring cucumber and squash plants in their gardens, while six groups of MGVs are managing and monitoring full sentinel plots. We have had no reports of downy mildew on cucurbits outside of northern Ohio and none in squash, pumpkins, gourds, or watermelons in any part of Ohio. We will continue monitoring and reporting downy mildew occurrences as they happen.

Cucumber downy mildew – photo by J. Amrhein.

If you suspect cucurbit downy mildew on your farm or in your garden, please send pictures (as close-up as you can) of the tops and undersides of affected leaves to me by text (330-466-5249) or email (miller.769@osu.edu).  Please include your name and the name of the town or city nearest you.

Downy mildew sporulating in a lesion on the underside of a cucumber leaf. Photo by F. Rotondo.