The problem of incorporating useful genes from any wild species is the various barriers to crossing with the cultivated potato so that fertile hybrids can be obtained. This mating yielded several new hybrids, which have since been crossed with a range of wild relatives and with derivatives of commercial varieties. Lots of Good Traits To Choose From The wild Mexican species also resist early blight, which is associated with dry weather. Typically, the disease is seen in August when plants start to mature. But late blight attacks quickly and is capable of defoliating a field within a matter of weeks.
Early blight is slower and progressive.
Resistance to both diseases is needed to reduce reliance on chemicals. University of Wisconsin graduate student Joe Kuhl, working with Hanneman and ARS plant geneticist Michael Havey, has advanced the research by identifying the chromosome in S. pinnatisectum that confers resistance. We know there are a number of resistance genes in cultivated potatoes, but the fungus has matching genes that negate the action of the host's resistance genes. That means eventually the fungus may overcome this type of resistance. The ultimate resistance test is always in the field.