Melons, Pumpkins, Cantaloupes

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Updated: September 17, 2021

Plectosporium Blight in Some Pumpkin Fields this Year - 2021

I am seeing some plectosporium blight in a few pumpkin fields this year, not as bad as last year but still there. This disease will probably increase if we continue having frequent rains in some locations.
Updated: September 16, 2021

Using Silicon, Stimplex and Plant Resistance in Pumpkin Production Systems to Reduce Plant Disease Loss

Using Silicon, Stimplex and Plant Resistance in Pumpkin Production Systems to Reduce Plant Disease Loss
Updated: September 16, 2021

Sulfur Deficiency in Corn and Watermelon

In the last few weeks several sweet corn fields as well as some watermelon and even a few tomato fields have been found with sulfur deficiencies (figs. 1 and 2). In sweet corn symptoms often appear as green leaves with light yellow or green striping on the newer leaves (fig. 1). In watermelon symptoms appear as a light green or light yellowing of the leaves of newer growth (fig. 2). In tomato unless severe you usually do not see any visible sulfur deficiency symptoms in the field, but fruit set and quality could be worse
Sulfur deficiency symptoms in older and younger sweet corn
Updated: September 15, 2021

Southern Blight Found Throughout Maryland this Season

Southern blight is a fungal disease that is most common in the tropics and subtropics, but also is found in the SE United States in the summer. In Maryland we usually find it in the southern part of the state in counties like St. Mary’s, Charles and Wicomico. It has been found this year in more northern counties such as Frederick, Montgomery and Baltimore.
Updated: September 15, 2021

Plectosporium Blight Common in Pumpkin Fields this Year

By this time of the season I usually see pumpkin fields infected with powdery mildew pretty commonly throughout the mid-Atlantic. And while powdery is present in many pumpkin fields it does not seem as bad as in previous years.
Plectosporium yellow-tan spots (lesions) on pumpkin leaf
Updated: September 15, 2021

Ozone Damage to Cucurbit and Tomato Plants

I have been seeing some ozone damage to cucurbits and oddly to tomatoes over the last 2 weeks or so, which is not unusual with the hot hazy conditions we are having. Ozone is the most common air pollutant in the eastern United States.
Ozone damage to watermelon crown leaves
Updated: September 15, 2021

Manganese Toxicity in Cantaloupes

Growers may already be seeing leaf symptoms on their cantaloupe plants that are often misdiagnosed as a foliar disease. However, these leaf symptoms described below indicate manganese (Mn) toxicity which is related to low soil pH.
Updated: September 15, 2021

Maintain Pumpkin Foliage For as Long as You Can

One of the main things a grower can do to ensure a good quality pumpkin is to be sure they maintain their fungicide applications for as long as they continue to harvest fruit. Maintaining good foliage cover for your pumpkins results in pumpkin handles that are dark green stout and firm (fig. 1).
Harvested pumpkins with good handles
Updated: September 15, 2021

Gummy Stem Blight in Cantaloupe

Gummy stem blight (GSB) was found in an Eastern shore muskmelon field in the last few weeks. It is a cucurbit disease caused by the fungal pathogen Didymella bryoniae. This fungus is favored by cool to warm, rainy weather. It can infect a host at any stage of growth and affects almost all parts of the plant including leaves, stems and fruits.
Water soaked lesions on stems (red arrows) and tan lesions with necrotic areas on leaves (yellow arrows)
Updated: September 15, 2021

Frequent Heavy Rains = Lots of Vegetable Disease Problems

I do not have to tell you that these frequent and heavy rains we have been having over the last 2-3 weeks have really increased the amount of foliar and at times soil diseases in our vegetable crops. In cucurbits foliar diseases such as Alternaria, gummy stem blight and an odd one Cercospora (figs 1a, 1b) all have been found causing moderate to severe defoliation in some fields that are heavy with fruit.