Bacterial wilt does not only attack potatoes but also tomatoes and is hosted by a large number of weeds. After infection symptoms (wilting) become more severe under dry conditions, starting from the lower leaves, rapidly moving upwards and eventually killing the entire plant. The disease can be identified by its symptoms on the potato tubers, which show as a brown ring if cut open. Use of certified if possible disease resistant seeds, crop rotation and hygiene are the only ways to prevent bacterial wilt. Bacterial wilt enters the plant through small wounds that can be caused by nematodes, other sucking insects like aphids and whitefly and also through damage during weeding. It is spread through infected plant material, irrigation water and infected soil. Therefore hygiene is crucial. Infected plant material, leaves and tubers have to be removed and destroyed. Crop rotation needs to be practiced to stop infection cycles.
The first symptoms of late blight are leaf spots that enlarge and kill the entire leaf. The whole plant eventually rots away. In weather conditions that favor a blight outbreak fungicides should be applied regularly. Again hygiene in the field e.g. removal of harvest residues etc. is a must to control blight.