Hi all,
With many crops being removed from the field at UVM’s Catamount Farm and many other farms that we’ve visited, there has been a steep decline in documented pests/diseases. However, there are some pests that are persisting in fall crops.
Some of the highlights are below:
- There are growing reports of leek moth larvae being found on leeks within Vermont. Generally, the third flight of adults in August are the overwintering generation. These usually do not lay any eggs and head off to other areas to find a spot to be protected through the winter. However, when we have late season high temps, this can drive some of those adult moths to continue to mate and lay eggs on available alliums (i.e. leeks). This is what we presume is happening in the region, given the surge of warm temperatures this August. Any larvae that you are currently seeing are certainly the last generation. At this point, if you are seeing larvae, preventative measures are not effective.
- Mexican bean beetle populations are still being seen in significant numbers in Chittenden County, VT. As mentioned last week, there is a biological control (a paratsitoid wasp) that has shown some promise for controlling the beetle in the early stages of an infestation. You can find more information here: Mexican Bean Beetle Biological Control
- Swede midge damage continues to be a problem in late season brassicas. Some of the most susceptible crops from our scouting are collards, russian kale, brussels, and broccoli. Some smaller scale organic growers have reported success in reducing swede midge damage using insect exclusion netting. For broccoli, removing the netting after heads are formed seems to work well.
- Late season berries are showing increased amounts of Spotted Wing Drosophila.
- Corn earworm is being found in and around the region on many farms. Growers are reporting high numbers in Massachusetts and traps in the region are confirming large regional populations.
- Though we have yet to see allium leaf miner in Vermont, it is known to occur in NY, Mass, and CT. The fall flight of adult flies generally occurs from mid-sept through October in the region. Be on the lookout for a line of white dots on the aboveground foliage of late season alliums.
As we have been consistently reporting, fungal leafspot diseases have taken their toll this season. Also, (Please click on any of the highlighted links for fact sheets related to the disease of interest)
- Alternaria in brassicas; Alternaria and Septoria leafspot in tomato; Cercospora in beets, etc. Protectant fungicides applied weekly will help protect new tissue.
- From regional extension networks, “Many poor looking tomatoes at this point: early blight, bacterial canker, septoria, nutrient deficiencies, hornworm defoliation, powdery mildew and leaf mold in tunnels, etc”
- As reported last week, we are seeing downy mildews in young brassica seedlings. Downy mildew in cucurbits has not been diagnosed in the state yet, but it is all around us.
- Late blight has been found in potatoes in Maine and in Wisconsin but there is no imminent threat at this point. Choanephora rot is common on summer squash due to rains. Watch out for phytophthora fruit rot in pumpkins if soils are rain saturated for 24 hours.
| Spotted Wing Drosophila | Blueberries, Raspberries | SWD larvae populations are being found in increasing numbers in late season berries. An easy way to test for SWD in your crops is to use the salt float method. Click here for instructions on the salt float method: Salt Float Test. |
| Colorado Potato Beetle | Potatoes | CPB is all but absent from most potato fields that we are monitoring. Most have moved to overwintering sites in the margins of fields. |
| Leek Moth | Onions/Garlic | Farmers are reporting leek moth larvae in leeks. See recent highlights above. |
| Striped Cucumber Beetle | Squash/Cucumber | We are still seeing the remnants of bacterial wilt in various squash and cucumber plots. |
| Squash Bug | Squash | Squash bug nymph infestations have really picked up due to egg masses beginning to hatch. Though most plants are tolerating the infestations. |
| Flea Beetle | Broccoli/ Kale | Flea beetle populations are rebounding and we are seeing increasing damage in late season brassica plantings. Damage in beets is also being reported on farms in the northeast. |
| Swede Midge | Kale/Broccoli | Swede midge damage continues to be found extensively in susceptible brassica crops and the highest pressure we’re seeing is in russian kale varieties, Brussels, and collards. A reminder that the tell-tale “blind heads” and scaring can generally be found at the center of the plant. Also, any strange growth like twisted leaves and stunted growth may also be a sign of infestations. |
| Imported Cabbage Worm, Diamondback Moth | Broccoli and Kale | Cabbage Whites continue to be seen flying around brassica plots. Brassicas are tolerating ICW damage. Diamondback moth chrysalises are being found frequently. |
| Squash Vine Borer | Winter and summer Squash | Squash vine borer has largely not been a problem on many of the farms that we’ve been visiting this summer. |
| Onion Thrips, Onion Downy Mildew | Onions | Thrips damage is extensive in onions across the region. Many farmers are reporting considerable amounts of onion thrips damage. However, with the harvest of most onions occurring in the region, control measures have largely been abandoned. |
| Tomato/Tobacco Hornworm | Tomato | We’re seeing more caterpillars arrive in tomato plots. The pressure, however, does not seem to be very significant. |