Fusarium Fruit Rot of Muskmelon

Posted: August 29, 2012

In the past several weeks Fusarium fruit rot has been confirmed in several commercial muskmelon fields in Pennsylvania.
Fusarium fruit rot lesion on muskmelon (Photo: Beth K. Gugino).

Fusarium fruit rot lesion on muskmelon (Photo: Beth K. Gugino).

Fusarium fruit rot can be caused by several different soiborne Fusarium spp. which are different than the Fusarium species that commonly cause vascular wilts in cucurbits. Many of the infected fields had been experiencing periods of heavy rain in addition to warm temperatures. These extreme fluctuations in moisture and temperature can leave muskmelon fruit prone to cracking and infection. The pathogen can also infect at the soil-melon interface. Following infection, the initial lesions are small and surrounded by a green margin. As the lesion matures, larger cracks can develop along sutures that run the length of the fruit and secondary organisms can enter further degrading the fruit. Under high humidity, white to pink fungal growth may also be observed near the crack or when the infected fruit is cut open.

Regular irrigation to reduce drought stress will help reduce cracking and minimizing potential wounding of the fruit in the field or at harvest will reduce potential points of entry for the pathogen.  Reducing direct fruit contact with the soil through use of cover crops, mulches or strip tillage will reduce soil splashing on the fruit. There is not an effective fungicide for managing Fusarium fruit rot primarily because is difficult, if not impossible, to adequately cover the fruit especially where it comes in contact with the soil. Post-harvest treatment of the fruit with a disinfesting/sanitizing solution may help reduce post-harvest losses. Be careful to rogue out infected fruit or let them sit for several days post-harvest before being placed in bins. Infected fruit can deteriorate rapidly in storage bins and ruin the entire container. Muskmelon cultivars may differ in their susceptibility due to differences in rind characteristics so make notes at harvest as too much cultivars may have had more or less disease.