Plant Fungal Diseases | University of Maryland Extension

Updated: October 21, 2024

Orange Rust is a bigger problem than usual this year in brambles

The recent weather has been damp with overcast skies and drizzle, which can lead to foliar diseases like botrytis and orange rust in brambles. Orange rust appears as blister-like masses of orange aeciospores on the lower leaf surfaces of blackberry plants, caused by fungal pathogens. Infection occurs after prolonged wetness, with temperatures between 43°F and 72°F.

Fig. 1 Orange pustules on the underside of bramble leaves indicating infection with Orange rust. Photo: T. Sievers, Blumen Farm

Updated: October 21, 2024

Turfgrass Diseases-Dollar Spot (FS-2023-0665)

Dollar spot is a common fungal disease that affects turfgrass, particularly high-maintenance ones like golf courses. It can also damage athletic fields and home lawns. The disease is caused by several species of the fungal pathogen Clarireedia spp. which infects the turfgrass through leaf tissue. Dollar spot appears as circular or oblong discolored spots, about the size of a silver dollar, with brownish-tan color. It can affect various turfgrass species, with creeping bentgrass and annual bluegrass being highly susceptible, while tall fescues, perennial ryegrasses, and Kentucky bluegrasses are moderately susceptible. Zoysiagrass and bermudagrass are less susceptible but can still be damaged under favorable conditions. The disease thrives in temperatures between 60°F and 85°F (15°C and 30°C) with high humidity and prolonged leaf wetness. Effective management includes using resistant cultivars, proper irrigation, fertility management, mowing practices, rolling, topdressing, and dew removal, as well as biological and chemical control methods. Fungicides are commonly used, but they should be rotated to prevent resistance development. Integrating these practices helps prevent and reduce the severity of dollar spot outbreaks on turfgrass. Author: Fereshteh Shahoveisi; Title: Turfgrass Diseases: Dollar Spot (FS-2023-0665)

Updated: October 21, 2024

Club Root Found in Brassica Crops

Clubroot caused by Plasmodiophora brassicae is a major disease of brassica, i.e., broccoli, cabbage, turnip, rutabaga, and radish. It can also infect weeds in the mustard family as well as some grasses.

Fig. 2 Club root disease on fibrous crucifer roots.

Updated: October 21, 2024

Plectosporium blight in many pumpkin fields

Plectosporium yellow-tan spots (lesions) on pumpkin leaf

Updated: October 21, 2024

Tar Spot Update: First Reports

Map of the Mid-atlantic showing cases of tar spot

Updated: October 21, 2024

Selected Fungicides and Bactericides Labeled for Greenhouse Use

Updated: October 16, 2024

Physiological Tomato Fruit Disorders

Updated: October 16, 2024

Sunscald Very Prevalent in Peppers This Year

I know this seems very obvious to most growers as we have sunscald every year in our vegetable plantings. This year just seems to be especially bad as I have gotten several calls from growers about a strange problem in their peppers that looks like sunscald, but couldn’t be. The reason given that it could not be sunscald is because the plants have thick foliage and the fruit seem well covered.

Updated: October 16, 2024

Tomato Plastic Mulch and Shade Study 2012

Tomato plants were transplanted on 7 May 2012 into black (grower standard), white or reflective plastic mulch.

Tomato plants covered with 30% shade, July 5, 2012

Updated: October 16, 2024

Industrial Hemp Production in Maryland: Frequently Answered Questions (FS-1172)

As industrial hemp production becomes legal in the US, new and experienced growers alike have questions about its cultivation, management, and marketing. This factsheet answers frequently asked questions about hemp production in Maryland. Information contained within this document is current as of June 2021. The UMD Industrial Hemp webpage (https://extension.umd.edu/programs/agriculture-food-systems/program-areas/fruit-vegetable-production/alternative-crops/industrial-hemp) will house the most updated information on hemp production in Maryland. Authors: Nichole M. Fiorellino, Emily Zobel, Karen Rane, and Andrew Ristvey; Title: Industrial Hemp Production in Maryland: Frequently Answered Questions (FS-1172)