Pumpkin growers are in the middle of their season now, with plants still flowering, fruit being set, and set fruit sizing up. We’ve been getting steady rains in South Charleston for the past two weeks, and the pumpkin plants are as large as I’ve ever seen. My research plots with small vining hybrids are planted on 15′ centers but are now nearly 12′ wide, even after vine training!
Steady rains have favored pumpkin growth.
Powdery Mildew has been detected at the station on 7/22 but is still at very low levels, under 0.5%. This is the equivalent of 1-2 white powdery colonies per leaf which is a very low level. Growers are encouraged to begin their spray schedule oevery7-14 days when they see the first colonies, as this disease multiplies very fast in the canopy. For a list of PM fungicides, see the Cucurbit chapter of the Midwest Vegetable Production Guide (https://mwveguide.org/uploads/pdfs/Cucurbit-Crops_2024-12-03-155451_othe.pdf) or take a look at some of the results performed at OSU over the past few years (https://u.osu.edu/jasinski.4/pumpkins/).
Early powdery mildew infections on upper leaf…only a few percent in this image.
While Downy Mildew has been reported in Ohio over the last two weeks, it is the clade that affects cucumbers not pumpkin. Protective applications of chlorothalonil or mancozeb will help protect against infection; recall that FRAC M fungicides like chlorothalonil and mancozeb can be added to every spray with only minimal chance of resistance development. Once DM has been positively identified in a field, switch to more specific and systemic products found in the MVPG.
Squash bug activity has been picking up in the plots over the past few weeks, with all stages readily seen on foliage; eggs, nymphs and adults. The threshold is one egg mass or adult per plant to justify an application. There are not squash bug specific sprays per se, and any insecticide application made at this point needs to consider if the plants are flowering or not. If flowering, legal pollinator protections and guidelines must be followed to minimize impacts on pollinators and other beneficial insects in the field. Applications of pyrethroids or other insecticides will kill many of the beneficial insects and most likely spike secondary pests like aphids. Do not add a blanket insecticide unless you have a specific pest insect above threshold that needs to be controlled. If an insecticide is needed, do not tank mix with a fungicide as this will increase bee mortality in most cases; apply late in the evening to lessen impact on pollinators. Available insecticide options can be found in the MVPG.
Squash bug life stages.
Other News from Around the Research Station and Beyond
The Tar Spot sweet corn study is nearly ready to begin evaluating. Tar Spot is a relatively new disease on corn, first detected on field corn in Ohio in 2018. Currently the plants are at V7. When the plants reach V10, the evaluation for dark brown stroma on leaves will begin. This project is also being trialed at Piketon and Muck Crops station. We’ll keep you updated as the season progresses.
OSU researchers are working with FarmSense to evaluate a new kind of insect monitoring device that does not rely on a sticky card or compartment to trap the insect. Instead, the experimental FarmSense device reportedly can identify the pest moth as it flies through the sensor. Pest detections are then uploaded via cellular connection to the cloud where growers can access trap counts on a website without taking time to visit the trap. This technology is being compared to standard Heliothis traps for squash vine borer and corn earworm. Stay tuned for more results.
FarmSense traps differ from other conventional traps.
Brown Marmorated Stink Bug traps are being set to record the late summer migration toward tree fruit and other vegetables, especially sweet corn, tomato and pepper. Keep an eye out for these pests as you work around your fields.
BMSB traps deployed.