Further south, Stewart's wilt is a common disease due to the mild winter temperatures which allow high numbers of corn flea beetles to survive. If the winters are exceptionally warm, Stewart's wilt may become a problem on sweet corn as far north as southern New England. The last time this occurred in Connecticut was in 1991. I was working with 10 sweet corn growers on the UConn IPM program. The yellowing is caused by the bacterium accumulating and clogging the vascular system of the plant which interrupts the upward flow of water and nutrients.
Infected plants appear stunted and wilted.
The plant often succumbs to the disease soon after leaves show necrotic lesions. A good field test to confirm the presence of the disease, involves making cross-wise cuts through the stems at the soil line of a few plants showing yellow leaf discoloration. The presence of a brownish cavity and soft rot in the pith indicate a severe stem infection due to Stewart's wilt. Disease Management Floating row covers used to enhance crop earliness, prevent the transmission of the disease by excluding the corn flea beetles from the plants during the seedling stage. Many varieties are now available with a range of resistance to Stewart's wilt.