Powdery Mildew Detected – This week marks the first week powdery mildew was detected in the pumpkin plots in South Charleston at the Western Ag Research Station. There have been reports of PM being found a week earlier in Wayne County. At the station, the amount of disease detected in the trial was extremely minor; only three white colonies on ca. 60 leaves, top and bottom leaf surfaces inspected, on July 18. Powdery mildew can multiply in the canopy rapidly given warm and humid conditions so the recommendation is to begin treatment when the first colonies are discovered. Today, nine treatments for the powdery mildew fungicide trial on pumpkins were applied. Major fungicides being tested include Milstop, Cease, Switch, Gatten, Procure and Quintec. Results of the trial will be reported when the trial is completed mid-September.
Striped Cucumber Beetle Update – The summer generation of striped cucumber beetles emerged in South Charleston around two weeks ago and have moved off of the foliage and primarily into flowers at this point in the season. Treatment for beetles in the flowers is not recommended as this will only cause significant harm to pollinators in and around the field, plus cause other issues with pest insects (see below).
Sticky panel with rootworm attractive lure
On a related note, the striped cucumber beetle attractant study being conducted at the Western Ag Research Station is about ¾ done at this point. Of the three attractants being tested for striped or spotted cucumber beetles, none seem to stand out as being hyper attractive to these two beetles. There is one lure that is very effective against the Western corn rootworm beetle, which has also begun to emerge from corn fields in the past few weeks.
Aphid infested pumpkin plant
Green lacewing egg in center of circle
1 black circle around ladybug eggs, 2 circles around golden aphid mummies
Aphids Rising…But Why? – What do you get when you apply a pyrethroid insecticide to a pumpkin field in early July? Answer, most likely a field full of aphid covered plants. Why the surge in aphids? This is attributed to the highly toxic nature of the pyrethroid chemical class to natural enemies in the field that are actively suppressing the aphid population. In the photos, you can see some major aphid predators re-establishing on the aphid infested leaves; ladybug eggs, green lacewing eggs and aphid mummies (evidence of parasitoid wasps). The lesson here is unless you have a known pest to control in a pumpkin field which is over threshold, resist the urge to spray a broad-spectrum insecticide. If a treatment must be made, consider selecting products that are less likely to flair aphids or other secondary pests.
In an IPM context, it is important to protect plants with fungicides from diseases such as powdery or downy mildew when they are detected above threshold. Over the past few years, researchers have begun to understand the importance of not adding both fungicides and insecticides to the same tank mix due to harmful synergies, some that are known and many that are unknown, on pollinators and potentially other insects like natural enemies. For a deeper dive into the negative synergy of mixing fungicides and insecticides, Cornell University recently published this bulletin. https://cornell.app.box.com/v/ProtectionGuide-FieldCrop2023.
Cornell Pollinator Guide
World’s smartest toad?
Amphibian Pest Management? – While scouting for powdery mildew on Thursday, I came across this toad cleverly parked at the edge of a pumpkin flower, no doubt waiting for a juicy opportunity to nab a few beetles or bees. First time I have ever seen this!