Pumpkin Anthracnose

2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38

Among pumpkin crops, anthracnose most often affects cucumbers, as well as melons with watermelons. Pumpkin attacks this disease much less often. Cucumbers grown in greenhouses are especially strongly affected by the merciless anthracnose. And in the open field, leaves with fruits mainly suffer from this unpleasant ailment. This disease is widespread almost everywhere - it can be encountered in the Far East, and on the territory of the Volga region, and even in the North Caucasus

A few words about the disease

The manifestation of anthracnose can be seen in almost all above-ground parts of vegetation, as well as on the root collars. The first symptoms of infection may appear already on young seedlings - on their root collars, as well as on cotyledons. As for adult plants, their anthracnose often affects the leaves and fruits.

Anthracnose almost always appears on the leaves in the form of rather large rounded specks of a yellow or light brown hue. Subsequently, from the leaves, this ailment gradually passes to the stalks and petioles with fruits. On stalks with petioles, oblong brownish specks are formed. The symptoms of anthracnose are most pronounced on fruits, on which you can see round and slightly depressed spots-sores of a brownish hue (and in watermelons they can be black). At high humidity, on these spots, reddish-yellow or pinkish small pads appear in the form of concentric circles.

The causative agent of this disease is the fungus Collelotrichum lagenarium. Its development takes place in the conidial stage. And this stage manifests itself in the form of pinkish pads forming on the affected areas of vegetation. In autumn, at the end of the growing season, a very unpleasant black sclerocial tissue (mycelium plexus) is also formed at the sites of lesions on the crusts of the fruits.

The spores of the causative fungus during the growing season spread rather quickly with the help of insects and wind, as well as with raindrops. The harmful fungus enters the tissue of stems and fruits through damaged areas, and into the leaves through the stomata.

Anthracnose develops quite strongly when wet weather is established. And especially favorable for its development is the combination of high temperatures (from 22 to 27 degrees) with high humidity (about 90%). The duration of the incubation period under such a set of conditions is very short and is only 3 - 4 days. This greatly contributes to the massive infection of cultivated crops.

The overwintering of the harmful fungus takes place on infected plant debris, especially on fruit peels. Also, the spores of the fungus can persist quite well on the surface of the seeds.

How to fight

During the period of growing pumpkin crops, it is very important to follow the basic agrotechnical rules. Infected seedlings must be discarded, and decaying fruits, along with plant residues, must be promptly eliminated from the site and immediately destroyed. Thickening the planting is also by no means worth it. It is equally important to follow the rules of crop rotation, returning pumpkin crops to their former areas only after a few years. Good results can be achieved by introducing anthracnose-resistant varieties.

Before sowing, it is recommended to pickle seeds with fentiuram or TMTD (80%). Also, periodically it is necessary to pollinate crops of various crops or to spray them. For these purposes, colloidal sulfur, suspensions of zineb or phthalan, one percent Bordeaux liquid, and a suspension of copper oxychloride are suitable.

During transportation of fruits, as well as during their subsequent storage, in order to avoid contamination, they should be protected from any mechanical damage. And the stored fruits of melons and watermelons for preventive purposes are also recommended to be dusted with sulfur - 0.5 kg is taken for a thousand fruits.