Rotate with sweet potato, cassava, taro, but not with other cucurbits. The fungus can survive in the soil, living on plant remains. Do not plant cucumbers in land where cucurbits were grown last crop.The fungus can remain alive in stems on the soil surface for several months and release spores when wetted. Collect and burn, bury or compost the debris as soon as the harvest has finished.Remove weeds so air can circulate around the plants to hasten the drying of wet leaves.Remove wilted or dead leaves frequently as they may contain spores of the fungus.Sterilise the knife frequently by wiping it in 1% bleach. Harvest carefully, cutting the fruit from the vine do not pull them off.Avoid overhead irrigation as water splash spreads this fungus, or if overhead irrigation is used, apply early in the day so that the plants dry quickly.If many leaves, consider using a fungicide (see below). If spots are seen on the leaves, remove them to delay the spread of the disease. After planting, check the seedling at least twice a week.Do not plant cucumbers next to older cucurbit crops that may already have gummy stem blight.Sterilise the soil by heating it for one hour, either (i) in a half 44-gallon drum over a fire, or (ii) in an earth oven over hot stones, and covered by leaves or damp sacks.Sterilise the soil and/or spray the next lot of seedlings with a fungicide.If there are many spots, do not use any of the seedlings throw them away and start again.If spots are present, remove the plants and burn them. Check for leaf spots, at least every 2 days.Do not make the nursery downwind from cucurbits fields (otherwise the wind and rain will blow spores onto the nursery).Make the nursery far away from any other cucurbits fields.Take soil only from areas where cucurbits (e.g., cucumber, melon, watermelon) have not been grown before.Carefully choose the soil and site for the nursery:.Development of the disease depends on how long the leaves, stems and fruits stay wet so that spores can germinate, infect, and for the fungus to continue to grow.
Spread is by splashing water, wind-driven rain, and on fingers, knives and clothing during cultural operations. Survival is by the dormant cottony growth of the fungus and thick walled resting spores (called 'chlamydospores') inside the undecomposed remains of crops. Symptoms on the fruit can continue to develop in storage, when they become more obvious. Spots on fruit are oval to round at first, they have a greasy green appearance, later they merge, and develop into a brownish-black rot (hence the common name of black rot). If the spots grow around the stem, it dies. A sticky golden liquid may be present, which is characteristic of the disease, and the reason for its name.
Tiny black dots that are the spore-producing structures (fruiting bodies or pycnidia) cover these areas. On the stems, pale brown spots occur at wounds where leaves and fruits have been removed. Commonly, there is heavy leaf fall (Photo 3). The decayed areas are light brown, sometimes with a yellow margin extending back into the leaf (Photo 2). Spots and areas of decay often occur at the tips and other places along the margins of the leaves (Photo 1).
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