Plant Fungal Diseases

A very unusual and seldom seen tomato foliar blight was found by an intrepid county educator in Southern Maryland last week.

Severe outbreaks of downy mildew in garden impatiens (Impatiens walleriana) were reported first reported in the fall of 2011 on landscape plantings in Europe as well as in the US (Northeast, Midwest). In Maryland, the Plant Diagnostic Lab received its first infected sample in early June 2012. If you grow garden impatiens, it is important to be on the lookout for this disease.

Managing gray mold (Botrytis) on strawberries is increasingly challenging because of fungicide resistance development, plus a new Botrytis species that is less susceptible to fungicides is becoming common in the mid-Atlantic region. Resistance to certain fungicides is also a problem in management of anthracnose fruit rot. This article describes disease management strategies designed to slow further resistance development, while also providing specifics for managing our two most common fruit rots. Authors: Dr. Mengjun Hu, Univ. of Maryland, and Kathy Demchak, Penn State Extension

As you’re scouting fields this summer, keep this fungal disease in the back of your mind. Tar spot is a fungal disease of corn caused by Phyllachora maydis. It was first discovered in the United States in 2015. In Latin America where tar spot is more common, another fungal species, Monographella maydis, is known to occur in complex with P. maydis; however, only P. maydis has been found in the United States.

Agronomy News-October 2022, Volume 13, Issue 7. Topics in this issue are Survey of the Most Common and Troublesome Weeds, Farm Emergency Action Plan, Preparing for 2023: Small Grains Disease Management, Maryland Accepting Proposals for 2023 Animal Waste Technology Fund, Scouting For Ear and Stalk Rots in Corn, Keep An Eye On Nitrogen Fertilizer Prices, Grain Market Report, Weather Outlook, and Regional Crop Reports.

Distinct lesions patterns along leaf veins are signs of anthracnose disease on shade trees.

Black Root Rot found in strawberry plantings in the Mid-Atlantic this season.

Downy mildew is now a year-long challenge for grape growers in the East. Downy mildew is often difficult to manage because it requires specific weather conditions to become a serious threat, but it can develop into an epidemic very quickly in favorable weather.

Botrytis is a major disease threat as harvest approaches. Botrytis cinerea is a fungus that affects many plant species, especially wine grapes, where it is commonly known as Botrytis bunch rot or gray mold.

Trials were established at the Wye Research and Education Center in Queenstown, MD (WYE), Central Maryland Research and Education Center in Ellicott City, MD (CMREC), and Western Maryland Research and Education Center in Keedysville, MD (WMREC) in 2022 to assess the efficacy of select fungicides for the suppression of soybean foliar diseases.