Hi all,
As harvest season ramps up, we’re observing a decrease in insect pressure on the primary crops we’ve been monitoring. However, there are some important signals to watch for in the coming weeks that could be crucial for managing potential pest outbreaks.
We found the first sign of Basil Downy Mildew on a susceptible variety of Genovese basil last week in Burlington. BDM can severely affect basil plantings and, if left untreated, can lead to complete crop loss. The telltale sign of BDM is a grayish color (from the developing spores) on the underside of basil leaves. It may sometimes appear as if soil has settled on the bottom of the leaf. If you suspect BDM, you can place the affected leaves in a Ziploc bag with a wet paper towel to encourage sporulation. Yellowing between the veins on the topside of leaves can also be an indicator of a potential outbreak.
A resource for identifying, reporting, and managing BDM is the Ag Pest Monitoring Site for basil. Though it seems from our checking on the site, that submissions for validated occurrences are not as consistent as in past years. Nonetheless, it is helpful to check if you are ever wondering. In recent years, some resistant cultivars have been developed. These cultivars and information on them may be found on the monitoring site too.
For those folks that have some later onion varieties in the ground or a good investment in leeks, we are seeing a high number of adult leek moths in our traps, suggesting that the latest flight is peaking. If you are going to be harvesting over the next week or so, be aware that their may be some larvae or eggs in the leaves of your onions. We saw quite a few larvae feeding during our most recent onion harvest at the UVM research farm. Topping is always a good option in that case. Not to mention, a significant amount of mildew and rot due to the consistent heavy rains this season.
Colorado potato beetle adults are emerging again and laying eggs on the undersides of potato plants. This new generation, combined with high pressure from early leafhoppers and increased precipitation, has severely affected many of the potato crops we’ve been monitoring. However, we are seeing some positive effects in our later plantings and research on delayed planting. While we haven’t analyzed the data yet, it appears that missing the emerging spring population of Colorado potato beetles might be a good strategy.
Updates from other nearby regions:
- Late blight found in Spartansburg, PA and Cattaraugus County, NY (8/13) and also in northern ME now, the same strains as the ones found in late blight infections in Ontario, Michigan, and New York this year.
- Corn earworm and fall armyworm now in Northern New York
- Alternaria leaf blight on cucumbers, watermelon, cantaloupe in Long Island
As always, our website for the scouting reports can be found here. In addition to the pests reported here, our website also has a more comprehensive list of pests. The list also documents the progression of many common pests as they emerge throughout the season.
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.
Cheers,
VEPART Team
| · Pest | Crop | Observations |
| Colorado Potato Beetle | Potatoes, Solanums | Most populations are mixed stages, but adults have emerged for another generation and are laying eggs! |
| Squash Bug | Cucurbits | Adults and Nymphs are prevalent as normal for this time of year |
| Striped Cucumber Beetle | Squash, Cucumbers | Less bacterial wilt than previous yeasr |
| Flea Beetle | Kale, Collards, Cabbage | Not much of a problem at this stage, but we have an eye out for the latest brassica plantings. |
| Cabbage worms | Kale | Imported cabbage worm larvae are decimating some plantings and are especially prevalent in red Russian kale |
| Potato Leafhoppers | Potatoes, Beans | Leaf burn is extensive in various crops |
| Tarnished plant bug | Strawberries, potatoes | Tarnished plant bugs are being found in relatively high numbers in various crops. Some outbreaks in lettuce have been severe. |
| Leek Moth | Onions/Garlic | Latest flight is peaking and we are seeing larvae already in our harvested onions |
| Squash vine borer | Winter and Summer Squash | Pressure has been very high these days and this year! |
| Mexican Bean Beetle | Beans | Seeing larvae, adults and damage. Not extensive but some small outbreaks |