Rutgers University | New Jersey Agricultural Experiment Station | Pesticide User Responsibility

Andy Wyenandt

This is an archive of Dr. Wyenandt's posts on the Plant and Pest Advisory.

June 30, 2022

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.

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.

Filed Under: Vegetable Crops Tagged With: ,
June 29, 2022

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: , ,
June 28, 2022

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:
June 28, 2022

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: ,
June 27, 2022

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 on tomato
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.

For the homeowner or non-commercial grower there are a number of Rutgers/NJAES Fact Sheets available on-line:

Rutgers University/NJAES Fact Sheet (FS547) ‘Diagnosing and controlling important fungal pathogens of tomato in the home garden‘.

Rutgers University/NJAES Fact Sheet (FS548) ‘Diagnosing and controlling Phytophthora blight in the home garden’.

Rutgers University/NJAES Fact Sheet (FS1124) ‘Vegetable disease control recommendations for the home garden’.

For other Rutgers University/NJAES Fact Sheets for tomato please click here.

Filed Under: Vegetable Crops Tagged With:
June 27, 2022

Organic Production: Suppressing Soil-borne Pathogens in 2022

Pathogens such as Fusarium, Pythium, Phytophthora, Thielaviopsis and Rhizoctonia that cause pre- and post-emergent damping-off can cause serious problems in organic (and conventional) production.
The key to controlling and/or suppressing damping-off pathogens with biological controls is keeping the biological populations high and continually present on root surfaces of the host, and by following good cultural practices. [Read more…]

Filed Under: Organic Production, Vegetable Crops Tagged With: ,