Fungi

Fusarium wilt in Watermelons is caused by the soil borne pathogen Fusarium oxysporum f. sp. Niveum and several new races have been identified in Maryland.

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

Tar spot in corn, Tar spot is a foliar disease of corn caused by the fungus Phyllachora maydis. This disease has the potential to significantly impact yield.

Tar spot is a foliar disease of corn caused by the fungus Phyllachora maydis and we confirmed it for the first time in Maryland from a grower field in Harford County in 2022; however, it is likely that it has been present in fields at low levels earlier than the 2022 growing season. Weather conditions across northern Maryland and Southern PA in August and September were favorable for tar spot development and pockets of disease outbreaks were reported, leading to much discussion about the disease amongst farmers and ag service providers over the 2022-2023 winter months about what to do to manage this disease in the future.

2021 soybean fungicide trial results

Strawberry Botrytis fruit rot, also called gray mold (fig 1), is a common disease that typically drives fungicide sprays throughout a season. Flowers are considered the gateway for the pathogen, and some flower infections can stay latent until the fruit ripens while some may show up earlier at green berry stage under wet and cool conditions.

Tar spot, a foliar disease of corn caused by the fungal pathogen, Phyllachora maydis, was reported and confirmed for the first time in Maryland. County PA in 2020 and has since spread to several neighboring counties. It was first detected in the United States in Illinois and Indiana in 2015 and has rapidly spread throughout the Corn Belt. The sample collected from a Harford County farm on August 19 is the first confirmed case in Maryland.

The grape root borer (GRB), Vitacea polistiformis (Harris), is an insect pest native to the Eastern United States. Its range is from the central Midwest (west) to the Atlantic Ocean (east) and from Florida and Texas (south) to Vermont and Michigan (north). GRB is a pest of all commercial grape types and feeds on native Vitis. It has a long life cycle and takes many years for it to do significant damage to grapevines. However, once grape root borers are present in a vineyard, the unlimited susceptible food source can dramatically increase the infestation. The grape root borer effect may not be immediately apparent on the vines, but once the number of larvae reaches a sufficient level, damage can be significant. Because it is an ("invisible") root tunneling pest, many growers are unaware of the economic damage being caused by GRB.

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

Fruit and Vegetable News, Volume 13, Issue 1 (April, 2022). Topic in this issue are: Check for Allium leaf miner in onions and leeks over the next few weeks, Edema problem in high tunnel tomatoes, Using Plant Growth Regulators to Improve Apple Return Bloom, Botryis Fruit Rot (Gray Mold) and Crown Rot in Strawberries, Spring Pest Scouting in Strawberries, and Early Spring Vegetable Insect Scouting Tips.