Squash Vine Borer

Adult Squash Vine Borers (SVB) emerge from the soil around mid- to late June. Egg laying begins soon after as the adult female moths find thick-stemmed cucurbit crops like summer squash, zucchini, pumpkins and select varieties of winter squash. Fortunately, thin-stemmed crops like cucumber, watermelon, and butternut squash are less habitable for the larvae and therefore less likely to be impacted.

Most of the damage from SVB is done by larvae tunneling and feeding within the stems or vines. An early indication of SVB being present includes plant wilting that disappears at night when transpiration slows. You can also scout for tiny larval entry holes near the base of the vine. You might also find sawdust-like frass near the holes that signal an infestation.

You can monitor SVB with Scentry Heliothis pheromone traps from June through early August. The threshold for spraying is 5 moths/trap for vining cucurbits. Once larvae have bored inside the stem, insecticide application will have little control, so begin protecting your crops promptly. Thoroughly treat the base of stems to target hatching larvae. Some selective materials used for caterpillars in squash, such as spinosyns and Bacillus thuringiensis aizawi, have demonstrated efficacy in trials. A late or second crop of cucurbits can be planted in early July to avoid peak egg laying activity.

See the New England Vegetable Management Guide for more information on insect control options for SVB.

Fulvia Leaf Mold in High Tunnel Tomatoes

Recent hot, humid weather in combination with tomato plants rapidly growing in density creates the perfect environment for fungal diseases like leaf mold. It first appears as yellow or pale green spots that are not defined by leaf veins or margins. On the underside of leaves, olive green mold spots also forms. Over time, leaves may wither, die and drop. In more extreme cases, blossom and fruit infections can occur. Infected blossoms will turn black and fall off. For fruit, the stem will turn black and the leaf mold will progress to cause sunken, dry and leathery fruit rot

To control the spread of leaf mold, it is critical to improve airflow and reduce humidity by venting, pruning, and checking the placement of fans to ensure proper ventilation. Maintain night temperatures higher than outside air temperatures to reduce condensation You can also remove infected foliage to slow the spread of the disease. Sanitize tools and equipment, and when working within the crop, always begin in the healthiest sections first.

At the end of the crop cycle, remove and destroy all plant residue. Sanitize the tunnel before the next season and start with certified, disease-free seed or treat seed with hot water bath. Spray options for greenhouse and high tunnel tomatoes can be found using the New England Vegetable Management Guide.

Scarab Beetles

The white grub is a larva of a scarab beetle. The grubs will feed off the roots of grasses and weeds in early spring as they work their way towards the soil surface. There are several species of scarab beetles that the grubs will emerge as, including Asiatic garden beetles, Japanese beetles, June bugs, and Oriental beetles. The adults will feed on the foliage of many varieties of vegetables, herbs, and fruit crops including asparagus, basil, okra, and sweet corn.

Some scarab beetles are active at night so if you notice foliar feeding damage on plants during the day without signs of a culprit nearby, it might be due to an Asiatic garden beetle. For chemical control options, check the label of commonly used broad specturm synthetic pyrethroids carbamates, and neonicotinoids to see if scarab beetles are listed. Organic options include entomopathogenic fungus such as Isaria fumosorosea Apopka Strain 97 and beneficial nematodes such as Steinernema and Heterorhabditis species.

Continue to be on the lookout

The following pests that were covered in the previous pest alerts and are still relevant in current conditions:

• Allium Leafminer
• Aphids
• Colorado Potato Beetles
• Corn Earworm
• Cucumber Beetles
• European Corn Borer
• Flea Beetles
• Potato Leafhoppers
• Cabbage Root Maggot
• Onion Thrips
• Mites