Identify please( pest/disease on veg.)

Question: Michigan.  This is something on a watermelon vine in a greenhouse. I can't see it clearly (age) but I'm guessing it's insects. Is it enough to pull and remove from the greenhouse or is something additional needed to prevent further infestation of the next plants? Another place in building are squash vines with much mildew on leaves. Again, is removal from building enough to prevent infection of the next crop? I can provide more pictures if needed. Computer being unhelpful tonight.

responder: *Please Note: If there is mention of trade names in this response, it is for general information purposes only. It does not constitute an endorsement of one product over another, nor is discrimination intended against any product.  Thank you for contacting Ask Extension. Please contact us again with any gardening questions you may have, or call the MSUE State Hotline at 1-888-678-3464  Replied October 10, 2024, 5:31 PM EDT
response: Hello, I have a couple of questions for you. Is this your own personal greenhouse or is it a commercial greenhouse? I want to make sure you're on the right site. Also, could you send a few pictures that are closer to the black spots on the leaves and also on the top leaf that looks like it has white bumps on it? They could be holes in the leaf, but I can't be sure. I can't focus the picture to get a clear idea of what the black spots are. They may be insects.  If you could send close-up photos of the two areas in question, I might be able to get a clearer idea of the problem.  As to the mildew problem: there are two common types of mildew found on plants, powdery mildew and downy mildew and powdery mildew. Could you also send a photo of that plant?  Thank you and I'll wait for your response.

responder: The Question Asker Replied October 12, 2024, 10:40 AM EDT
response: The greenhouse is part of a city-wide project. It is 20 x 30 I'm guessing. Has large fan at one end can pull air in, 2 temperature-responsive exhaust louvers at the other. During cold, portable heater keeps winter temp at +/-60 F.  There are individual raised beds on edges and 2 down the middle. The black and white dots seem to be insects. They have spread to some okra plants in another bed.

responder: The Question Asker Replied October 12, 2024, 10:45 AM EDT
response: Additional pictures for viewing

responder: *Please Note: If there is mention of trade names in this response, it is for general information purposes only. It does not constitute an endorsement of one product over another, nor is discrimination intended against any product.  Thank you for contacting Ask Extension. Please contact us again with any gardening questions you may have, or call the MSUE State Hotline at 1-888-678-3464  Replied October 13, 2024, 3:09 PM EDT
response: Hello Gudrun, Your squash plant has powdery mildew. Poor air circulation and uneven temperatures are ideal for powdery mildew to grow and spread. The following is from an excellent article by the University of Minnesota Extension about the management of powdery mildew. I think you will find it helpful.  Powdery mildew weakens the plant and the fruit ripens prematurely. Infected plants produce fewer and smaller fruit.  In warm, dry conditions, new spores form and easily spread the disease. https://extension.umn.edu/disease-management/powdery-mildew-cucurbits  About your watermelon plant, the insects on the underside of the leaves are most likely aphids. The eggs are deposited on the underside of the leaves.  Also from UMN Extension: Aphids are very common insects and are found on most plants in yards and gardens. In most cases, they cause little or no damage to the health of plants. Signs of severe aphid feeding are twisted and curled leaves, yellowed leaves, stunted or dead shoots, and poor plant growth. https://extension.umn.edu/yard-and-garden-insects/aphids#garden-aphids-316410  I believe you will find both of these articles very helpful in managing powdery mildew and aphids.  In the meantime, please contact Jeremy Jubenville at <personal data hidden>. He is the horticultural greenhouse educator. He can give you insights about how to help you manage the conditions that may promote the problems you have.  If you need more information or have questions, please don't hesitate to contact me again.  Have a great fall!

responder: The Question Asker Replied October 13, 2024, 3:20 PM EDT
response: Thank you so much for the identification and suggested remedies.  I look  forward to  healthier plants in the future.  Gudrun  On 10/13/2024 3:09 PM EDT Ask Extension wrote:

responder: *Please Note: If there is mention of trade names in this response, it is for general information purposes only. It does not constitute an endorsement of one product over another, nor is discrimination intended against any product.  Thank you for contacting Ask Extension. Please contact us again with any gardening questions you may have, or call the MSUE State Hotline at 1-888-678-3464  Replied October 14, 2024, 8:47 AM EDT
response: You're most welcome. Wishing you a healthy harvest!