Month: August 2017

Are Pumpkin and Squash at Risk for Downy Mildew in Ohio?

Severe downy mildew on pumpkin, 2015.

Downy mildew has still not been confirmed on pumpkins and squash in Ohio, although the disease is widespread on cucumbers and melons throughout most of the state. This is the time of year when we really start to look for downy mildew on squash and pumpkins, as strains of the pathogen that attack these crops move into the area from the south, usually aided by remnants of hurricanes or tropical storms that reach Ohio. Remnants of tropical storm Harvey are likely to reach southern Ohio at least by Friday. Downy mildew spores can be transmitted long distances in the air, and are brought to the surface by rain.  We are particularly concerned with outbreaks reported in Kentucky on butternut squash this week (http://cdm.ipmpipe.org/scripts/map.php), an indication that the pathogen is established in the area and can serve as a source of inoculum for areas to the north and east.  Growers in southern Ohio should be especially vigilant, although we recommend stepped-up scouting of pumpkins and squash, and application of protectant fungicides, throughout the state.  Fungicide recommendations can be found in my June 28 post.

Corn earworm present at high density

As reported in VegNet last week, the corn earworm population is on the increase in Ohio. At our research farm in Columbus, there were 60 corn earworm moths caught in our pheromone trap during the previous week (13-19 August), and this increased to 577 moths caught in the week that is now ending (20-26 August). Sixty moths in one week is considered to be moderate pest pressure, while 500 moths in one week is considered to be very high pest pressure. Sweet corn that is in the silking stage is at risk of infestation by corn earworm larvae unless it is sprayed with insecticide every 3 days. Details about spray intervals based on trapping can be found at: http://u.osu.edu/pestmanagement/files/2014/12/CornTrapInstructions2009-u47rp3.pdf . Beware that when earworm moths are abundant, control by pyrethroid insecticides (Warrior, Mustang Maxx, Baythroid, Asana, Permethrin, Brigade) has tended to be fair to poor during the past few years due to the development of resistance. Alternative insecticides are Coragen, Radiant, Blackhawk, and Lannate. Entrust is a good option for organic production.

Sweet corn that is genetically engineered to produce the B.t. toxin, as in the Attribute and Attribute II hybrids from Syngenta, and the Performance hybrids from Seminis, offer some protection from infestation by earworm and other caterpillars. These B.t. hybrids were excellent for caterpillar control when first introduced, but in the past few years, hybrids in the Attribute and Performance series are showing only moderate protection from earworm if not supplemented by insecticide sprays, whereas the Attribute II hybrids are still showing excellent control of earworm and other species. A supplemental insecticide spray can be applied when 75-100% of plants have fresh silk, which is a few days later than the typical first spray on non-BT corn.

Weekly catch of corn earworm at several sites is shown on our online Ohio trap report page: https://docs.google.com/spreadsheets/d/10gh3rHahdxLKkXQapGyEPxWsjHYRmgsezOoFHnwtyEo/edit?usp=sharing , where there is a tab for this species and several other pests along the bottom of the sheet.

 

Cucurbit Downy Mildew Update – Two More Ohio Counties

Map of downy mildew reports in Ohio (all on cucumber or melon) and neighboring states, August 21, 2017. Red indicates reports within last 7 days. www.cdmipmpipe.org

Downy mildew was confirmed on cucumbers in two additional Ohio counties late last week: Harrison and Licking. We still have not confirmed downy mildew on pumpkins or squash in any part of Ohio.  On today’s Cucurbit Downy Mildew ipmPIPE conference call,  none of the representatives from nearby states (MI, WV, VA) reported seeing downy mildew on pumpkins or squash yet this season. However, downy mildew has been reported recently  on jack-o-lantern pumpkins in two counties in northwestern Indiana.  Careful scouting of pumpkin and squash fields should remain a priority.

Downy mildew can be confused with powdery mildew at very early stages of the latter (before the white powdery colonies appear), especially if the pale yellow areas on the top of the leaves are very dense.  Symptoms of other diseases including angular leaf spot and bacterial spot can also be confused with those of downy mildew.  If in doubt, please send a sample to your county educator or directly to the OSU Vegetable Pathology Lab in Wooster, OSU-OARDC, 1680 Madison Ave., Wooster, OH 44691; ph. 330-263-3838.

We are in the process of evaluating commercially available fungicides for efficacy against downy mildew using a bioassay. We will have results within a few weeks. However, we are not aware of new fungicide failures in other parts of the US this season, so our fungicide recommendations posted on June 28, 2017 remain in place.

Corn earworm alert

Every year in August, we are on the lookout for the arrival of large numbers of corn earworm moths that migrate into Ohio from the southern USA. Over the past three days, we have seen a surge in the catch of corn earworm moths in our pheromone trap in Columbus; the catch from Monday (8/14) to Wednesday (8/16) was 11 moths, but the catch from Wednesday (8/16) to Friday (8/18) was 41 moths, with a total of 60 for the full week. We have corn earworm pheromone traps at eight other locations in Ohio; last week these were reporting a catch of only 0 to 3 moths in one week, but it is likely that the catch at these other locations will show an increase during the coming week. Now that most of Ohio’s grain corn is starting to dry out, any patches of sweet corn will be more likely to be attacked by this pest. Once corn earworm is detected, silking sweet corn should be sprayed with insecticide every 2-6 days to prevent injury to kernels. The choice of an appropriate spray interval is as important as the choice of product to use. Details about the most appropriate spray interval based on pheromone traps are shown in the chart below.

Although the corn earworm is the key pest of sweet corn, European corn borer and fall armyworm are two other pests that sweet corn growers should be aware of  at this time of year.  The second generation of European corn borer (ECB) is now underway but it has been slow to start and is present at low density at all nine Ohio sites where we have traps. This pest will be infesting sweet corn as well as peppers. On sweet corn, ECB can be controlled by the spray schedule used to control corn earworm. On peppers, ECB can be controlled by insecticide sprays every 7 days. Fall armyworm (FAW) activity in recent weeks has been variable, with only a trace of FAW moths detected in traps in Columbus, Celeryville, and Wadsworth but FAW moths have been more abundant at South Charleston. Damage by fall armyworm is often most noticeable in whorl-stage corn but it can also be severe in silking corn.

Weekly catch of these three moth pests is shown on our online trap report page: https://docs.google.com/spreadsheets/d/10gh3rHahdxLKkXQapGyEPxWsjHYRmgsezOoFHnwtyEo/edit?usp=sharing , where there is a tab for each pest along the bottom of the sheet.

More Ohio Counties with Cucumber and Melon Downy Mildew

Cucumber downy mildew

Downy mildew continues to take a toll on cucumbers and melons throughout the state. We have numerous reports of downy mildew on these two crops from northern and central Ohio, with new observations confirmed yesterday in Hardin and Greene counties.  Downy mildew is best managed by preventative fungicide applications – a list of effective fungicides can be found in my June 28, 2017 post.

We still have not confirmed downy mildew on pumpkins or squash anywhere in Ohio.  However, downy mildew has been reported on butternut squash in Blair County in central PA, and on jack-o-lantern pumpkins in Starke County, in northwestern IN.  It is a good idea to scout all cucurbits if you have not yet seen downy mildew in your area, and maintain a protectant fungicide program.  Keep in mind that on squash and pumpkins, powdery mildew can look like downy mildew in the early stages before the white powdery mycelium is seen.  Many of the fungicides used to manage these two very different diseases are fairly specific to either one, so be sure to have an accurate diagnosis.

Last Call – Pumpkin Field Day Aug. 17th

The Pumpkin Field Day will be later this week on Thursday, August 17th, from 6-8PM at the Western Ag Research Station in South Charleston.

Pumpkin plots at the research station.

This year’s field day will offer beginning and experienced growers valuable research updates regarding disease management, insect management, weed control, and showcase some new pumpkin and winter squash varieties.  Celeste Welty (entomology), Claudio Vrisman (plant pathology), Bryan Reeb (weed control), and Jim Jasinski (IPM Program and emcee) will be on hand to share their knowledge and answer your questions. There be presentations on how to identify and control weeds, insects, and diseases on this crop.

The field day will feature some traditional and new projects on the wagon tour, including a seven-treatment powdery mildew fungicide demonstration trial, a powdery mildew drip irrigation trial, a pumpkin variety trial with 20 hybrids ranging from small to large fruit, and a winter squash variety trial with 11 entries. This season has been marked by periods of heavy rain and cooler than average temperatures, resulting in a few hybrids that are a little behind schedule in terms of growth, having yet to produce any fruit. I anticipate by the field day they will have produced some fruit for you to see, although it may not be mature.

After the formal presentations, attendees will be encouraged to walk around the plots and interact with the specialists and other growers.

There is a fee of $5 per person; refreshments and handouts will be provided.

Pre-registration is requested by August 15th at www.surveymonkey.com/r/pumpkin17.

Here is the rough agenda for the field day:
5:30  Begin check in
6:00  Welcome, introductions, outline of field day
6:05  Board wagons and head to the plots
6:10  Orientation to plots, begin presentations
7:10  End formal presentations, begin plot walks
7:55  Board wagons, complete evaluations
8:00  Field day ends, travel safe!

See the preliminary flyer below for a few more details. Looking forward to seeing you there. Contact Jim Jasinski (jasinski.4@osu.edu) or 937-462-8016 for more information.

Pumpkin field day flyer.

Mild Temps, Clouds and Rain = Increased Late Blight, Downy Mildew Risk

Late blight on tomatoes. Photo by Wayne County IPM Scout Chris Smedley.

Late blight has been confirmed on tomatoes in Wayne and Ashland counties this week.  We also found downy mildew in basil, cucumber and melons in our sentinel plots in Fremont and Celeryville, OH. Downy mildew is assumed to be widespread on cucumbers and melons in Ohio, but we have not yet found downy mildew on squash or pumpkins. The late blight and downy mildew pathogens are related and all are favored by moderate temperatures, rain, high humidity and cloudy skies. Tomatoes, potatoes, cucurbits and basil should be scouted regularly and treated with protectant fungicides. Management recommendations have been posted this summer for all of these diseases.  See the following:

Late blight: conventional and organic management

Cucurbit downy mildew management

Basil downy mildew management

Hardin County Crop Walk

By Mark Badertscher – Hardin County OSU Extension, Agriculture and Natural Resources

Hardin County – Are you a commercial fruit and vegetable grower who is looking for ways to manage pest issues in your produce? Maybe you raise vegetables in your home garden have spots on the leaves.  Do you have berries growing on your property or fruit trees in your yard that are not producing like they should?  Hardin County OSU Extension has planned a fruit and vegetable Crop Walk program on Tuesday, August 15 from 6:00-8:00 pm to help answer these concerns.  This program will include an emphasis on fruit and vegetable production.  The location of the program will be 21613 County Road 200, Mt. Victory.

OSU Extension entomologist Dr. Celeste Welty and OSU Extension Horticulture field specialist Jim Jasinski will be providing information about insect identification and recommendations, along with Integrated Pest Management (IPM) techniques for fruit and vegetable production. Graduate students from OSU Plant Pathology and Weed Science have been invited to help growers with plant disease problems and weed control methods in produce.  Hardin County OSU Extension Educator Mark Badertscher will provide information on labeling honey, registering bees with the Ohio Department of Agriculture, and steps beekeepers and commercial produce growers can take to register their bees and crops with the Sensitive Crop Registry.

The program will be held outside so bring your lawn chair and umbrella in case of rain. There will be a diagnostic table so be sure to bring along any weeds, plant nutrition problems, plant diseases, and insect specimens for questions and answers.  The program will conclude with walk through a produce patch, pointing out fruit and vegetable issues and steps to properly manage them.

For more information about OSU Extension, Hardin County, visit the Hardin County OSU Extension web site at hardin.osu.edu, the Hardin County OSU Extension Facebook page or contact Mark Badertscher, at 419-674-2297.

Scouting – Squash Beetle – Hocking County

A bug that has been found in Hocking County starting in early summer is the Squash Beetle.  It was originally found on honeydew and muskmelon plants.

Squash Beetle adult on muskmelon leaf with feeding damage

 

They have migrated from the fruit to a nearby planting of mouse melon and have started to feed on the leaves and breeding.

Squash Beetle larvae on mouse melon leaf

 

University of Maryland Factsheet –> Squash Beetle

 

2017 Pumpkin Field Day Approaching!

We are under two weeks until the annual Pumpkin Field day on Thursday, August 17th, from 6-8PM at the Western Ag Research Station in South Charleston.

Pumpkin plots at the research station.

This year’s field day will offer beginning and experienced growers valuable research updates regarding disease management, insect management, weed control, and showcase some new pumpkin and winter squash varieties.  Celeste Welty (entomology), Claudio Vrisman (plant pathology), Bryan Reeb (weed control), and Jim Jasinski (IPM Program and emcee) will be on hand to share their knowledge and answer your questions. There be presentations on how to identify and control weeds, insects, and diseases on this crop.

The field day will feature some traditional and new projects on the wagon tour, including a seven-treatment powdery mildew fungicide demonstration trial, a powdery mildew drip irrigation trial, a pumpkin variety trial with 20 hybrids ranging from small to large fruit, and a winter squash variety trial with 11 entries. This season has been marked by periods of heavy rain and cooler than average temperatures, resulting in seven hybrids that are a little behind schedule in terms of growth, having yet to produce any fruit. I anticipate by the field day they will have produced some fruit for you to see, although it may not be mature.

After the formal presentations, attendees will be encouraged to walk around the plots and interact with the specialists and other growers.

There is a fee of $5 per person; refreshments and handouts will be provided.

Pre-registration is requested by August 15th at www.surveymonkey.com/r/pumpkin17.

Here is the rough agenda for the field day:
5:30  Begin check in
6:00  Welcome, introductions, outline of field day
6:05  Board wagons and head to the plots
6:10  Orientation to plots, begin presentations
7:10  End formal presentations, begin plot walks
7:55  Board wagons, complete evaluations
8:00  Field day ends, travel safe!

See the preliminary flyer below for a few more details. Looking forward to seeing you there. Contact Jim Jasinski (jasinski.4@osu.edu) or 937-462-8016 for more information.

Pumpkin field day flyer.