Losses incurred in asexual propagation of alfalfa clones
1948
Grandfield, C.O. | Hansing, E.D. | Hackerott, H.L.
The results of these experiments showed that Ascochyta imperfecta was the most destructive of the three fungi studied and no doubt will be the most difficult to control. The soil-borne fungi Rhizoctonia spp. and others may be controlled in the greenhouse by sterilization of the sand. Black-stem is apparently more difficult to control. The disease probably is brought into the greenhouse from the field in the original plant material from which the cuttings are made, thereby infesting the sand or soil used. Healthy cuttings become inoculated possibly by splashing when watering. Apparently it will be necessary to do two things to increase the number of healthy cuttings produced under these conditions, viz., sterilize both the sand in which the cuttings are set and the soil to which they are later transplanted, and practice certain sanitary methods in order to prevent the plants from which cuttings are to be made from becoming infected with black-stem or possibly other fungi before being brought in from the field. Peterson and Melchers stated that the inoculum for the fourth cutting originated chiefly from diseased crop residue from the first cutting. This being true, sanitary measures could be taken in the field by cleaning up and destroying old crop residue. When the last cutting is made, the plants should be cut close to the ground. Under the system of making cuttings at the Kansas Station, this easily could be done, as the plants selected are usually space-planted.
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