Hi all,
High temperatures continue to put a lot of stress on plants, leading to symptoms that can take many forms and may be mistaken for diseases. When contacting the diagnostic clinic, be sure to include observations about where and how the issue appears across your planting. This information will help their team more accurately diagnose the problem.
This week we are starting to see a few peaks in pests that have taken a bit longer to build up than the last couple of seasons. One pest that we are now starting to see in greater numbers is the squash vine borer, both in our traps and in plants. While they are often spotty in their distribution in a field, a large population can be quite problematic. The first signs of the pest will often be wilting, which may make you think of bacterial wilt transmitted by striped cucumber beetles. If you start to see some plants wilting in the field, look at the base of the plant and check for any stem damage or some of the insect excrement, also known as frass. That will be the tell for the presence of the pest. If the plant is not completely wilted, it is sometimes possible to do some quick removal of the larvae inside the vine with a knife and some delicate surgery. Once removed, you can try to bury the damaged part of the vine with some soil. If there is enough of a connection left, things may be possible to save.
Leek moth numbers have waned enough on most farms that it is likely safe to start removing any exclusion netting if you have been keeping alliums protected. With garlic harvest in full swing in most areas, be sure to look for the beginning of any larval feeding in the neck of garlic before bringing them into curing and storage areas. Our research has shown that most marketable damage to garlic from leek moth occurs when eggs or larvae hitchhike on the stems and feed down into the bulb as the neck dries down. Topping garlic and/or onions before curing or storage can significantly reduce the risk of post-harvest damage from leek moth in areas with large populations. That said, it is also looking like onion harvest might miss the next flight of leek moth!
Colorado potato beetles are really thriving this year. While high CPB numbers are no surprise in July, we are receiving numerous reports from organic growers about the emergence of spinosad resistant populations. With the loss of the Bt strain for CPB control and a lack of other potential organically approved chemical options, it was just a matter of time before resistance would crop up.
Our team continues to test the efficacy of some organically approved biopesticide options, particularly fungal sprays and some innovative new conventional options. We will keep you posted on the outcomes of those studies. In addition, we are again seeing good results with our delayed planting study. Our late June and early July plantings are showing greater vitality compared to the earlier May plantings, which are mostly sticks at this point. Finally, there are lots of growers using various tractor and human powered whacking and collecting methods. If folks would like to share their methods, it might be useful to collect those suggestions for a VVBGA post, a twilight meeting, or our upcoming UVM Catamount Farm and Field Day (see below).
Regional Roundup:
- Though we are yet to hear of any confirmed incidence of cucurbit downy mildew in cucumber or melons within Vermont, it is just a matter of time, as it seems to be around within the region (e.g. NY, CT).
- Corn earworm, aka tomato fruitworm, is being found on farms in Vermont, with reports of larvae in peppers and tomatoes nearby cornfields. Trichogramma parasitoid wasps can be an effective strategy if timed right.
- Maine is reporting incidence of Basil downy mildew, so be on the lookout in any non-resistant varieties.
Finally, as referenced above, we wanted to put on your radar an upcoming event at the Horticultural Research and Education in South Burlington:
HREC Farm and Research Field Day
When: August 13, 2025
Time: 2-5pm
Location: Horticulture Research and Education Center (HREC), 65 Green Mountain Dr., South Burlington, VT
UVM’s Catamount Educational Farm, in collaboration with the Department of Agriculture, Landscape, and Environment (ALE), is excited to host a Farm and Research Field Day at the Horticulture Research and Education Center (HREC) on Wednesday, August 13, from 2:00 to 5:00 PM.
We hope you’ll join us for an afternoon of sharing, learning, and connecting with all the research, farming, and outreach happening at the farm!
The day will include:
- Catamount Farm Tour – Explore and learn about the food production systems, educational initiatives, and community partnerships occurring on the farm.
- Field Research Tour – Check out the innovative research projects currently underway at HREC for a host of research projects for vegetable, fruit, and other specialty crop growers.
- Informational Exhibits –
Full Schedule will be sent to registrants and posted to various listservs as the date nears.
This is a great opportunity to connect directly with the diverse group of people working at the intersection of farming, teaching, and agricultural research.
Though registration is not required, if you plan to attend, please submit your name to this form.
Any Questions? Contact Vic Izzo (vizzo@uvm.edu) or Terry Bradshaw (tbradsha@uvm.edu)
For detailed management information about these pests, as well as a comprehensive guide to current production and pest management techniques for commercial vegetable crops, check out the New England Vegetable Management Guide. And, as always feel free to reach out to us if you have any questions, using our new submission form and/or directly emailing me at vizzo@uvm.edu
| Pest | Crop | Observations |
| Striped Cucumber Beetle | Squash, Cucumber | Even though numbers are still very high, we are not seeing a ton of bacterial wilt. |
| Squash Bug | Squash | We are beginning to see nymphs, as eggs begin to hatch, but most of the populations are in the egg stage. |
| Colorado Potato Beetle | Potatoes, Eggplant | While there are overlapping generations that this point, most larvae that we are seeing are getting ready to pupate in the soil. |
| Flea Beetle | Potatoes, Eggplant | Very low numbers, they are not fond of heat. |
| Leek Moth | Onions, Garlic | The most recent flight is beginning to wane, as the population moves into its larval stage. |
| Thrips | Onions | Thrips surprisingly are being found at lower numbers compared from previous years. |
| Cabbage worms | Kale | We are seeing some diamondback moth on some farms. Other cabbage moth caterpillars are present but not causing much damage. |
| Potato Leafhoppers | Potatoes, Beans | We are seeing some fields with PLH, but the pressure seems really low in most cases. |
| Tarnished plant bug | Strawberries, potatoes | Tarnished plant bugs are now being seen in various crops and some outbreaks are being reported. |
| Mexican Bean Beetle | Beans | Definitely a growing concern in beans on some farms, be on the look out |
| Swede midge | Brassicas | We are seeing outbreaks of SM on some farms but others are completely untouched. Damage is mostly in broccoli and collards. |