Hi all,
Though it feels like July this week, I can assure you that it is barely June. The record high temps have really pushed some pest insects into overdrive. Populations of pests that are typically peaking in mid-June, are already exhibiting high pressure in various crops. It is important to remember, however, that things tend to even out over the course of the season. Looking at the upcoming weather forecast in much of the region, we should be returning to more seasonal temps, which hopefully will slow some outbreaks.
Pest Week in review
One pest that is peaking relatively early this season is the three-lined potato bug. Don’t be fooled by its name, this pest is rarely found feeding on potatoes. For most growers and gardeners, the three-lined potato bug is a scourge of tomatillos. We are seeing large outbreaks of the pest in Chittenden County and reports of high pressure in the southern parts of the state. These beetles are often confused with striped cucumber beetles to the untrained eye, as they exhibit a similar striped pattern. However, the three-lined potato beetle displays a distinctly orange/red head and legs, contrasting with the yellow and black heads of striped cucumber beetle. Also, larvae of the three-line potato beetle feed upon the leaves of their host plant (and cover themselves in their own feces as a predator repellent!), in contrast to cucumber beetle whose larvae feed on plant roots. Growers that are yet to see the pest can protect their susceptible crops with exclusion netting or row cover. This approach can be rather effective. Once an outbreak has occurred within a planting of tomatillos, it is difficult to recover without a curative chemical application.
A few other highlights from the past week:
Leek moth: Scouting in garlic has revealed that many of the populations within the region are in the pupal stage with adult moths soon to emerge. The recent hot weather suggests that we are likely to see an earlier second flight in comparison to last year. With scaping just beginning in the plantings that we’ve been scouting, it could be a bad combination for those growers that value scapes for their markets. Our traps are yet to capture any second flight adult moths, but we will alert you once we see signs that the flight is beginning.
As mentioned last week, Colorado potato beetle adults are actively laying eggs in eggplant and potato plantings. We’ve even seen some colonizing field tomatoes. In the next week or so, those eggs will start to hatch, if they haven’t already. The larval stage of the beetle is the most damaging stage, so any control tactics should be timed accordingly.
Striped-cucumber beetles are colonizing cucurbits on many farms, and we suspect that pressure will build rapidly over the next couple of weeks. Kaolin clay applications (e.g. flat dunks) are a popular organic method for reducing pressure on smaller seedlings. The clay particles coat the leaves, reducing their attractiveness and physically deter beetles trying to feed upon the foliage.
Spinach/beet leafminer: We are officially seeing leafminer eggs and even some damage in spinach and chard. As we warned last week, early application of insect exclusion netting can be very effective managing leafminer damage. If you are seeing foliar damage, remove and destroy leaves showing active “mines” to reduce future pressure.
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.
vizzo@uvm.edu & slewins@uvm.edu
| Pest | Crop | Observations |
| Three-lined potato bug. | Tomatillos | We are seeing some large outbreaks in tomatillos |
| Leek Moth | Onions/Garlic | We are primarily seeing pupae and late instar larvae. The second flight will likely begin soon. |
| Flea Beetle | Arugula, kale, broccoli | Beetles are being found in high numbers in many brassica crops. Row covers can be an effective strategy for protecting vulnerable brassica seedlings. |
| Spinach leaf miner | Spinach | There are reports from Massachusetts that leafminer eggs are being found on various chenopod leaves, particularly chard |
| Cutworms: | Various crops | Cutworms are causing a lot of trouble in high tunnels and in the field. We’ve seen several large outbreaks in gardens around Burlington and on a couple of farms. |
| Colorado potato beetle | Eggplant | We are seeing CPB adults laying eggs on eggplant. We haven’t seen many larvae, but that will change very soon |
| Striped cucumber beetle | Cukes | Though most damage is being seen in high tunnels, there are certainly some outbreaks in the field. |