Hi all,
We had a one week hiatus from our scouting blog last week as much of our crew was on vacation. We were back in the fields this past week, and the consistent rains across much of the region have resulted in a spike in many leaf spot diseases, particularly in cucurbits. This is no surprise given the high humidity and consistent leaf wetness. Interestingly, we are not seeing as much powdery mildew as we have in previous years, nor are we seeing much septoria or other fungal disease pressure in tomatoes around the region. Perhaps this is because even when it has rained, it has often been followed by periods of intense heat that quickly evaporate moisture from leaf surfaces, reducing the opportunity for some diseases to establish.
Speaking of tomatoes, we are seeing a large surge in tomato/tobacco hornworms pressure in almost all of the tomato crops that we have been scouting. So, it is that time of year when you can dust off that 80s blacklight for the good of IPM! Yes, tomato and tobacco hornworms are becoming common throughout the region, and several farmers are reporting heavy infestations. One of the more fun and effective ways to scout for hornworms, especially in high tunnels, is to use a blacklight flashlight at night. Under ultraviolet light, the cuticle of hornworms fluoresces, making these otherwise well camouflaged caterpillars easy to spot and remove by hand. This approach is often much more effective than searching during the day, when hornworms blend in remarkably well with the foliage. By the time they become large enough to find easily in daylight, they have often already caused significant damage.
There are also some excellent native natural enemies of hornworms, particularly the parasitoid wasp Cotesia congregata, that can help suppress populations. Providing a continuous supply of small flowering plants throughout the season helps support these beneficial wasps. Research has shown that buckwheat is an excellent floral resource for C. congregata (as well as hover flies), with wasps feeding on buckwheat nectar exhibiting longer lifespans. For organic growers, products containing Bacillus thuringiensis (Bt) remain a very effective management option when caterpillars are small.
As we mentioned previously, swede midge pressure continues to be spotty across the region, but where it occurs it can be relatively severe. This season we have observed swede midge damage in several plantings of red cabbage. Historically, we have been less concerned with swede midge in cabbage compared to other brassica crops because the growing point becomes protected as the cabbage head develops. However, it has been interesting to see noticeable injury in red cabbage this year. This may simply reflect the timing of the population peak, but it is something we will continue to monitor. One of the rewarding aspects of this scouting program is that we are constantly learning new things about these pests as we observe them across different farms, production systems, and environmental conditions.
Another observation that has become increasingly consistent is that sprouting broccoli appears to be a relatively good host for swede midge. Our team has now documented this on several farms, particularly as sprouting broccoli has become more popular among growers in the region. Although swede midge injury appears to be more common in sprouting broccoli than in traditional heading broccoli, at least anecdotally, growers can often harvest around the damaged shoots and still produce a marketable crop under moderate infestations. We are planning another brassica swede midge trial next year to investigate some of these new observations more systematically, and we will be sure to keep you posted.
Also, as our team has been exploring best practices for delayed planting in potatoes to reduce Colorado potato beetle (CPB) pressure, we have heard from many growers, and observed on several of our scouting farms, that they are trying the technique. In addition, our delayed planting research trials are up and running as we speak. In most cases, delayed plantings are showing a significant reduction in CPB pressure. This is encouraging news and is in line with what our previous trials have shown.
A couple of important things are worth noting. First, we have primarily conducted these trials with day neutral or earlier season potato varieties to ensure there is ample time for the tubers to size up and develop a viable skin before harvest. Also, greensprouting can support this technique, as holding seed potatoes for an extended period under less than ideal conditions can lead to reduced germination rates and plant vigor. Greensprouting can help offset these issues while still allowing growers to delay planting. That said, if you are currently using delayed planting as part of your IPM strategy for managing CPB, we’d love to hear from you! We are planning to conduct an information session this fall or winter to share the results from our recent trials, discuss plans for new experiments to further dial in the technique, and collect grower input on their experiences. Hopefully, this will lead to a useful fact sheet to support both current users of the practice and growers interested in trying it.
Notes from around the region:
- Potato leaf hoppers are being found in the region on many farms
- Leek moth is beginning a third flight, consider topping if you have had significant pressure this year
- Corn earworm is spiking in the region
- Onion thrips damage has picked up, along with onion downy mildew, but yields on most farms has not been affected
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.
Finally, we would also like to acknowledge that funding for this year’s scouting program has been generously granted by VVBGA and the USDA Transition to Organic Partnership Program
Cheers,
vic
| Pest | Crop | Observations | ||
| Potato Leafhoppers | Beans | Populations are peaking in plantings where they have been found | ||
| Colorado Potato Beetle | Potatoes | Pressure is dwindling | ||
| Spinach/Beet leaf miner | Spinach, Swiss Chard, Beets | Relatively little to no damage this season | ||
| Striped Cucumber Beetle | Squash/Cucumber | Beetle populations are less apparent and not causing as much damage. It is also a bit difficult to scout with canopies so dense | ||
| Flea Beetle | Broccoli/ Kale | Pressure is picking up in newly planted brassicas | ||
| Three-lined potato bug. | Tomatillos | Pressure is declining | ||
| Mexican bean beetle | Beans | Still limited distribution. | ||
| Leek Moth | Onions/Garlic | Third flight is beginning | ||
| Spotted Wing Drosophila | Berries | Catching a few more these weeks, but populations seem smaller than past years | ||
| Swede Midge | Brassicas | Seeing consistent damage on most farms, mostly in more susceptible varieties of brassicas (red Russian kale, sprouting broccoli, brussel sprouts. | ||
| Squash Vine Borer | Cucurbits | Still seeing consistently high numbers | ||
| Squash Bug | Summer squash | Consistent pressure | ||
| Onion thrips | Onions | Damage is peaking but yields seem ok in most plantings. | ||