Sudden Wilt

Just before your cantaloupes, cucumbers, squashes, watermelons, and pumpkins are ready to harvest, they suddenly wilt and die, taking your crop with them.

Unlike slow wilts, caused by lack of water (or too much water), or vascular diseases, such as Verticillium wilt and Fusarium wilt, sometimes leaves of cucurbits droop suddenly, and the entire plant collapses. It is sudden wilt, also known as parawilt.

Sudden wilt is a soil-borne fungal disease that appears after heavy irrigation on hot, sunny days. Contrary to what you might expect, lots of water combined with hot sun is not what melons and squashes need. Sudden wilt occurs when there is an imbalance between water uptake and water loss, combined with certain fungi.

Sudden wilt symptoms

Sudden wilt starts as yellowing of the crown leaves, followed by total collapse of the entire plant. Death soon follows. If you dig up an affected plant, you will see that the roots are straw-colored or dark. There are three different fungi responsible for sudden wilt, and each one has unique symptoms:
•  Pythium spp. - appears as brown root rot
•  Acremonium cucurbitacearum - corky bands on discolored roots
•  Rhizopycnis vagum - upper portions of the taproot turn reddish and corky

Sudden wilt treatments

There are no chemical controls against sudden wilt. Careful water management, proper plant spacing, and removal of crop residue after harvest can help reduce the chance of sudden wilt in your garden. 

Monitor your cucurbits for signs of sudden wilt near the end of the growing season. Good drainage and 2- to 3-year crop rotations can help prevent this disease from wiping out your cucurbit crops. And let the soil dry out completely between waterings.