Additions of more than 20 pounds per acre of nitrogen at a time can result in splitting of carrots especially if rain or heavy irrigation occurs shortly after application. Nematodes are more likely to occur in fields where tobacco has been grown immediately prior to the carrot crop. In these situations, stubble from the preceding tobacco crop can reduce the effectiveness of the soil-applied fumigant. Nematodes within this stubble can escape being killed by the fumigant and result in larger early infestations in the field. Although populations will decline as the weather becomes cooler, early damage can be just as severe as damage later in the year.
Nematodes can cause roots to become forked and therefore unmarketable.
Although tobacco fits well logistically in rotation with carrots, with the potential for nematode and disease problems in carrots following tobacco, this practice is not recommended. Nematodes have occurred in carrots planted after tobacco.