Symptoms of Cucurbit Fusarium Fungus
Fungal diseases come in many forms. Fusarium fungus appears as both a wilt and a rot. It is almost a case of the chicken or the egg, as to which develops first. Fusarium rot of cucurbits primarily affects melons and cucumbers, and there are numerous species of fusarium which cause the disease. Cucurbits with fusarium rot often don’t show symptoms until they are harvested. The initial disease invades the fruit most often at the stem end. Mechanical injury seems to encourage infection. Secondary fungus often invades and compounds the symptoms. The plant itself may show no disease signs, minimizing the ability to diagnose the disease. Some species of fusarium cause red to purple discoloration while others create brown lesions. Cross sections of the fruit can indicate the fusarium species but little is to be done once the fruit is infected. Control of cucurbit fusarium rind rot relies upon cultural practices, fungicides, and careful handling of harvested fruits. Fusarium rot of cucurbits occurs during wet to moist ambient and soil conditions. Infection occurs most frequently where the fruit is in contact with soil. The disease appears to be contagious with harvested fruits that are diseased, infecting others in the stock. It is not known if the soil harbors the disease but it seems likely. It may also be spread by seeds from infected fruit. Good hygienic practices can minimize the spread of the disease. There are at least ten species of fusarium fungus which cause the disease. Each has a slightly different presentation but the end result is a slow spreading infection of fruit.
Prevention and Control of Cucurbit Fusarium Fungus
Good field practice can be crucial to minimizing fusarium wilt issues. Crop rotation, solarization of soil, removal of wild cucurbits which can host the disease, and verification of disease free seeds are all key to preventing the occurrence of fusarium fungus. Pre-harvest fungicides do not seem to affect the spread to a high degree but post-harvest applications are helpful. Immersing fruit in hot water for one minute or in a fungicide recommended for use on post-harvest fruit will prevent the spread of the disease to the rest of the harvest. Avoid injuring fruit which can also provide entry points for the fungus.
