Cucumber beetles emerge to feed on cucurbits anytime from the end of April until mid May. Use of a systemic insecticide drench (like Admire) will provide 3 to 4 weeks of protection. What is not appreciated is that the grubs of cucumber beetle also cause damage with their feeding on the roots. A systemic drench will afford some protection that a foliar product likely will not. Having an insecticide on the transplants from the beginning can aide against bacterial wilt, which the adults transmit. The striped one can arrive in dramatically large numbers and suddenly with a few hot days, so timing a preventative application to ‘just before needed’ can be tricky. The spotted ones usually show up a bit earlier and in less numbers, if that is of any help.
Spotted cucumber beetle (top) usually precede their striped cousin (bottom).
Maintain good weed control. It improves spray coverage to the crop, makes scouting easier, and reduces alternate habitat for the insect pest.
Apply a broad spectrum pesticide as soon as ‘tough to kill’ insect pests (e.g. stink bugs and squash bugs) are noticed. You’ll kill some of the adults, but maybe more importantly, you’ll have product on the foliage that will kill the nymphs which will shortly hatch. Some of these adults you are seeing are over-wintered females and are actively laying eggs.
Review how you might scout or monitor for insects pests in a more effective fashion. Some growers are using corn earworm and stink bug traps to better time their pesticide applications. Use of sentinel plants like Turk Turban can be an effective scouting method for cucurbits. Remember to scout at the right time of the day, in the right weather conditions (e.g. dry and warm times).
Apply insecticides in a way to protect pollinators as best possible. Late evening is preferred. Use products with less harmful residue. Establish a buffer area around hives and don’t apply product upwind.
Cucurbits - Rotate your fungicides between groups. While diseases resistant to common fungicides have not been reported in this area, it is always possible. Both SW Indiana and SE Missouri have resistant problems (see photo and caption). Do you understand the MOA code (Mode of Action)? Can you find it on the label or another resource? Have you evaluated your disease control program with this in mind?
Fungicide resistance has occurred in Indiana's premier melon region recently to powdery mildew and gummy stem blight.
Tomatoes - Can you tell the difference between Early Blight and Septoria, our two most common fungal diseases? Can you tell the difference between these and Bacterial Spot (or Speck), our two most common bacterial diseases? Foliar diseases have been a struggle the last two years because of the rainy and cool weather. Do you have your disease control program ready? Have you reviewed the latest production guide for any new products? Unfortunately there are none for bacterial problems, but have you reviewed Table 22 recently to see if you’re doing all you can with cultural management strategies?
Keeping up the nutrition of the crops reduces crop stress and lessens disease problems
(e.g. Fusarium wilt). Consider a plant tissue analysis for complete information when a problem develops that is unusual. (did you have your soil tested and did you put down preplant fertilizers accordingly?)
Note the disease resistance of the different varieties you have planted. Pay special attention to those ‘without resistance’ when scouting for diseases. A disease will likely first appear on the varieties lacking resistance.
Be aware of the ’unusual’ and follow up on your suspicions, should it occur. As mentioned adjacently, fungicide resistance has occurred. Late blight flared on tomatoes and potatoes in the NE US this past summer for the 1st time in years. Lastly, we have had occurrences of bacterial canker and some similar diseases not common in Missouri.