Authors: Marissa Schuh and Natalie Hoidal
We've continued to have bouts of rain, but growers are still getting field work and planting done. Pest issues are on the rise, and we have our first few days of hotter weather on deck.
General Notes
Rainy weather and N deficiency
The frequent and sometime heavy rains have led to nutrient deficiencies. Transplants are going in nutrient stressed in many spots after being held longer than anticipated, and rains have caused nutrient leaching. If plants are showing signs of nutrient deficiency, side dressing will be especially important this year. Quick release organic sources of N include blood meal and Chilean nitrate (check with your certifier before using this one, and be careful how you use it as it can burn roots).
Nitrogen deficiency appears as uniform yellowing in leaves. Photo: Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org
Deer
We have seen some spots where deer have done significant damage to transplants. If you’ve had deer damage in the past, or are growing in an area near deer habitat, the best time to take action on deer is before you see damage – once they’ve realized how tasty your vegetable crops are, it is hard to keep them away. While permanent fencing is the best option, this is expensive. There are lower cost, more temporary fencing available, such as 3D fences that are short in stature but work by messing with deer’s depth perception.
If you have already had documented damage this year, the Minnesota DNR has programs for specialty crop growers to help with deer management.
Crop Updates
Beans: We tend to see some sporadic bean leaf beetle damage in early June. The adult beetles that come out around this time typically defoliate bean plants a bit, and then they disappear after laying their eggs. When plants are small, this early feeding can cause significant damage. Beetles lay eggs in the soil. Larvae remain in the soil feeding on roots, and a second generation of adults emerges in late summer. This second generation often feeds directly on bean pods, which can make them unmarketable depending on your markets. For more information about spray thresholds and management strategies, read more about this insect here.
Brassicas: Planting continues. More pest issues are emerging, we recently published refreshers on flea beetles and caterpillars.
We have seen some spots where deer have done significant damage to transplants. If you’ve had deer damage in the past, or are growing in an area near deer habitat, the best time to take action on deer is before you see damage – once they’ve realized how tasty your vegetable crops are, it is hard to keep them away. While permanent fencing is the best option, this is expensive. There are lower cost, more temporary fencing available, such as 3D fences that are short in stature but work by messing with deer’s depth perception.
If you have already had documented damage this year, the Minnesota DNR has programs for specialty crop growers to help with deer management.
Crop Updates
Beans: We tend to see some sporadic bean leaf beetle damage in early June. The adult beetles that come out around this time typically defoliate bean plants a bit, and then they disappear after laying their eggs. When plants are small, this early feeding can cause significant damage. Beetles lay eggs in the soil. Larvae remain in the soil feeding on roots, and a second generation of adults emerges in late summer. This second generation often feeds directly on bean pods, which can make them unmarketable depending on your markets. For more information about spray thresholds and management strategies, read more about this insect here.
Brassicas: Planting continues. More pest issues are emerging, we recently published refreshers on flea beetles and caterpillars.
We may start to see splitting in radishes in areas that receive substantial rainfall in the next couple of weeks; consider harvesting a bit early if a major rainfall event is predicted in your area.
Cucurbits: Vine crop planting is ongoing. Cucumber beetles are starting to show up in some spots. You can refresh yourself on managing them here.
Garlic: Many farmers are harvesting garlic scapes this week. Ideally, scape harvest should be done by hand vs. mechanically to avoid damage and yield losses. Here’s an overview of yield damage from a previous Ontario vegetable update, which highlights just how significant the yield losses can be when plants experience damage from mowing:
Past research has shown that by accidentally removing one leaf when the scape was removed, bulb sizes were reduced by 13% and the yield was reduced by an average of 17.5%. The same trial showed that yield was greatly impacted as the number of leaves cut during mowing increased. If the top two leaves were cut, the yield was reduced by approximately 25%, almost outweighing any potential gains you would expect by removing the scape in the first place.
Another thing to look for is leek moth feeding damage on garlic scapes as harvest them. Squish any larvae or cocoons that you see on your garlic plants.
Leek moth caterpillars and feeding. Photo: Photo: Mariusz Sobieski, Bugwood.org
Peas: Harvest will begin soon in the Southern portion of the state.
Solanaceous crops: Tomatoes, pepper, eggplants, and ground cherries continue to be planted as weather allows. We are getting reports of three-lined potato beetle feeding. The crop they are most likely to cause economic damage to is tomatillos. You won’t find this insect on many insecticide labels. Three-lined potato beetle isn’t on many pesticide labels, though they are related to Colorado potato beetle. Read the label carefully to make sure the crop and setting you want to apply to is in the label if you want to use something on this insect.
Solanaceous crops: Tomatoes, pepper, eggplants, and ground cherries continue to be planted as weather allows. We are getting reports of three-lined potato beetle feeding. The crop they are most likely to cause economic damage to is tomatillos. You won’t find this insect on many insecticide labels. Three-lined potato beetle isn’t on many pesticide labels, though they are related to Colorado potato beetle. Read the label carefully to make sure the crop and setting you want to apply to is in the label if you want to use something on this insect.
We continue to get reports of cutworms, especially in peppers, tomatoes, and okra. We wrote about factors that determine cutworm pressure and talk about management options here.
Every year we’ve been seeing more and more cases of young transplants with stem girdling near the soil surface on black plastic mulch. Temperatures under black plastic can be 40-50 degrees hotter than ambient air temperatures, and when the air escapes through the holes created for transplants, this hot air can damage the stems of young pepper and tomato plants. It doesn't happen often enough to universally recommend that folks shouldn't use plastic mulch on peppers, but it happens enough that it's worth mentioning. Making sure peppers (and really any transplanted vegetables) are well watered and hardened off properly can help to prevent this from happening.
Recently transplanted pepper damaged by heat. Photo: Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org
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