Fusarium Watermelon

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

Fusarium watermelon begins to manifest itself from the stage of sprouting seedlings and until the formation of the second or third true leaves, as well as during the ripening of the fruit. Cultures heavily attacked by the disease often die 2 to 8 days after its external signs appear. And infection occurs mainly through the root system. If this unpleasant disease is not detected in time, the harvest of watermelons will not be as rich as we would like

A few words about the disease

On seedlings, Fusarium is manifested in two forms: wilting of root necks or their rot. In the first case, the cotyledon leaves lose their turgor, turn pale greenish shades, and then fade and dry out in just two or three days. And rot of the root collar in most cases occurs at a very low soil temperature or with too abundant moisture (and sometimes with a combination of these two factors). The root collars quickly become thinner and begin to rot, and the stems begin to shine through and become watery. Some time later, the infected seedlings break down and fall en masse.

As for adult crops, Fusarium also manifests itself on them in two forms: wilting and oppression. Often, the symptoms of its manifestation are confused with physiological wilting. In grown crops, wilting is characterized by exactly the same signs as in seedlings. In most cases, it covers individual stems. By the way, infected cultures do not always die - they often become dwarf and differ in small leaves and short internodes, and extremely small fruits are formed on them or are not formed at all.

The causative agent of this unpleasant scourge is the harmful fungus Fusarium oxysporum, the mycelium of which has an airy structure and is mostly painted in pinkish tones. True, sometimes it can have a light yellow or even white color. In this aerial mycelium, the formation of fusiform-sickle-shaped macroconidia, endowed with extremely thin membranes, occurs. Also, numerous microconidia are formed in the mycelium.

Fungal mycelium gradually begins to spread through the vessels of growing cultures, which in turn leads to disruption of various physiological processes and water metabolism. Moreover, the harmful fungus has a toxic effect on growing crops.

The causative agent of fusarium is almost always preserved on the remains of plants in the ground. And seeds are considered to be an optional source of infection - the pathogen is able to persist on their surface for a very long time. The intensive development of the fungus begins when the thermometer reaches twenty-five to thirty degrees. If the temperature rises above thirty-five degrees, then its development will begin to slow down, and it will stop completely only if the temperature drops to five degrees. With regard to soil moisture, the development of the pathogen is favored by an indicator of 50 - 80%. By the way, the causative agent of fusarium can easily develop and grow even on saline soils.

How to fight

The most important preventive measures in the fight against fusarium watermelon are the elimination of plant residues with their subsequent burning, the strictest observance of crop rotation (it is permissible to return the melon to its original place no earlier than five to seven years later) and deep plowing. Melon should be sown only after favorable predecessors, in thoroughly warmed up and sufficiently light-textured soil. If possible, it is advisable to use watermelon hybrids and varieties that are resistant to the pathogen.

Watermelons should be watered sparingly, trying not to flood the root collars of the plants. It is also useful to prepare a special composition for irrigation: 10 g of potassium salt, 30 g of ammonium sulfate and 125 g of superphosphate are dissolved in a liter of water. One to two liters of such a solution is consumed for each plant. And during the period of growing seedlings, watering watermelons with a fungicide called "Previkur" will serve well. This is usually done three to four times a week, spending two to four liters of solution for each square meter of crops.