Turkestan Alfalfa as Compared with Grimm for Wilt-Infected Soils in Iowa 1

Tests with Turkestan alfalfa have been in progress at the Iowa Agricultural Experiment Station since 1926 and have included 27 lots of imported seed and 2 domestic lots of Turkestan origin. Of about 500 lots of alfalfa included in yield trials at the Iowa Experiment Station, Turkestan, Hardistan, and Ladak are the only kinds that have demonstrated marked resistance to bacterial wilt, Phytomonas insidiosa McC. Under conditions of relatively poor drainage these alfalfas have also demonstrated their superiority in cold resistance to the variegated alfalfas generally grown. Turkestan, however, is particularly susceptible to leaf diseases. Hardistan is also susceptible but apparently to a lesser degree. Statistically, the probability is high that as long as stands of Grimm are maintained it will yield more than Turkestan. Apparently, it is necessary for the grower of Turkestan alfalfa to sacrifice a ton or more of hay per acre as a total for two or three crop years. With varieties susceptible to bacterial wilt profitable crops usually have been harvested for three crop years on wilt-infected soils at the Iowa Agricultural Experiment Station. Apparently the loss in yield from growing Turkestan is more than enough to pay the cost of reseeding when the greater value of the residue in the short rotation is considered. It would seem, however, that Turkestan has a place on wilt-infected soils of Iowa for those growers who desire to sacrifice yield to gain longevity. Turkestan does not have a place in Iowa where bacterial wilt has not yet made its appearance. In a 2-year test Hardistan and Turkestan gave similar results. The choice of varieties for wilt-infected soils in Iowa appears to lie between Cossack, Grimm, Dakota, or Montana common for short rotations and Turkestan, Hardistan, and Ladak for long rotations. For soils not infected with bacterial wilt farmers may well continue to choose the variegated alfalfas.