Vegetable Crops — Page 94 — Plant & Pest Advisory

Vegetable Crops Edition

Seasonal updates and alerts on insects, diseases, and weeds impacting vegetable crops. New Jersey Commercial Vegetable Production Recommendations updates between annual publication issues are included.

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June 30, 2022 Andy Wyenandt

Recognizing Angular Leaf Spot in Cucurbits

Angular leaf spot is common in New Jersey and the region. It often shows up during cooler, wet weather and isolated rain.

Symptoms of angular leaf spot in cucurbit.

Angular leaf spot of pumpkin. Note the 'shot holes' in the leaf.

Angular leaf spot of pumpkin. Note leaf ‘shot holes’.

Angular leaf spot will first appear as, small water-soaked lesions which will expand until they reach a larger leaf vein resulting in the angular looking symptoms on leaves. Under heavy disease pressure, the bacteria will infect fruit causing small, water-soaked circular spots. In many cases once weather conditions become dry again, infected tissue in leaves will die and fall out leaving the characteristic ‘shot hole’ symptoms. Control of angular leaf spot begins with the application of labeled rates of fixed copper plus mancozeb to help suppress the spread of the disease until hot, dry weather returns.

June 29, 2022 Kris Holmstrom and Joe Ingerson-Mahar

Vegetable IPM Update 6/29/22

Sweet Corn

Low numbers of European corn borer (ECB) moths remain a sporadic, low component of blacklight trap catches. Feeding in whorl and pre-tassel stage is now less common, as control has been applied to infested plantings and later blocks (now in whorl stage) have avoided most of the egg laying period. Slightly higher adult activity is in scattered pockets around the state (see map below at right). ECB injury over the threshold of 12% of plants infested, while still around, has generally been declining over this past week. We expect feeding wind down over the next week or so as we move into the period between generations.

Look for the characteristic “shot-hole” type of feeding (photo below at right) and consider treating when infested plants exceed 12% in a 50 plant sample. As plantings proceed to the pre-tassel stage, ECB larvae may be found in emerging tassels (see photo at left). It is a good idea to treat individual plantings as they move into the full tassel/first silk stage one time. This eliminates any ECB larvae that have emerged with the tassels as they begin to move down the stalk to re-enter near developing ears.

Useful insecticides for this particular application include synthetic pyrethroids (IRAC Grp 3), spinosyns (including OMRI approved Entrust) IRAC Grp 5), and diamides such as Coragen or Vantacor (IRAC Grp 28) or materials such as Besiege which include the active ingredient in Coragen. Synthetic pyrethroids alone should NOT be used for corn earworm (CEW) protection on silking corn. Control with these materials is very inconsistent.

The highest nightly trap catches of ECB for the week ending 6/29/22 are as follows:

Bellemeade 1	Farmingdale 1	Morristown 1
Blairstown 1	Georgetown 1	New Egypt 1
Centerton 1	Lawrenceville 1	Princeton 1
Crosswicks 1	Matawan 1	Sergeantsville 1

[Read more…]

Filed Under: Organic Production, Vegetable Crops

June 29, 2022 Andy Wyenandt

Preparing for Anthracnose and Alternaria Leaf Blights in Cucurbit Crops

Anthracnose and Alternaria leaf blight can become problematic in cucurbit crops during long periods of wet, humid weather. Both can cause significant losses if not controlled properly. With the production season in full swing, now is a good time to review a few of these important diseases. [Read more…]

Filed Under: Vegetable Crops Tagged With: alternaria, anthracnose, cucurbit crops

June 28, 2022 Andy Wyenandt

Don’t Rely on Disinfestants for Disease Control

The hot, then windy, then wet weather these past few weeks have brought with it prolonged windy days and rain to many areas. In general, this type of weather is ideal for the development and spread of many vegetable diseases.

By now most growers are on weekly protectant fungicide programs to help prevent disease development. It’s important to remember at this point in the season when disease pressure is high that growers stick with their standard fungicide programs.

Growers should not replace fungicides with disinfestant-type products in their weekly fungicide programs.

Remember, disinfestants only kill what they come into direct and immediate contact with and do not offer any residual activity like fungicides do. Disinfestants should be used in conjunction with weekly fungicide programs and be applied based on specific weather events such as following rainfall or overhead irrigation or after certain cultural practices such as tying or pruning where plant injury or wounding may occur.

Filed Under: Vegetable Crops Tagged With: disinfestants

June 28, 2022 Andy Wyenandt

Preparing for important fungal diseases in Asparagus during the summer.

Asparagus growers should consider scouting their fields during the summer months for foliar disease development. Important pathogens that growers need to scout for on a regular basis include Purple spot, Cercospora, and Rust. [Read more…]

Filed Under: Vegetable Crops Tagged With: asparagus, rust

June 27, 2022 Andy Wyenandt

Diagnosing Important Diseases In Tomato – Reference Guide

The following images consist of important diseases in tomato. These images can be used as a quick reference for diagnosing important fungal and bacterial pathogens. For best results, please turn your device (i.e., cell phone) sideways. For information on commercial control recommendations, please visit the tomato section of the 2022/2023 Mid-Atlantic Commercial Vegetable Production Guide. Additional information for home gardeners is located at the bottom of the Table.

Early blight	Septoria leaf spot	Anthracnose fruit rot

Early blight lesion on fruit	Ground rot infected green fruit	Ground rot sporulating on fruit

Bacterial leaf spot	Bacterial canker	Bacterial speck

White mold	Southern blight	Late blight on foliage

White mold sclerotia in infected stem	Southern blight sclerotia on infected stem	Late blight infected fruit

Collar Rot caused by Alternaria spp.