Influence of time of planting of potatoes in indiana muck soil on yield and scab development

Summary

Time-of-planting experiments were conducted with potatoes on the Northern Indiana Muck Soils Experimental Farm, near Walkerton, Indiana, during the period from 1939 to 1942. Both total yields and yields of marketable or essentially scab-free potatoes, were determined for crops from plantings made at 5 two-week intervals from about the 5th of May to the 5th of July.

Total yields decreased with each successively later planting, whereas scab severity increased to a maximum during the third or fourth planting. Scab severity decreased on the last planting in 1942.

In four experiments, in which Irish Cobbler was included twice; Katahdin, 4 times; and Sebago, once, the average total yields per acre were 365, 327, 261, 170 and 76 bushels, respectively. The yields of tubers sufficiently free from pitted and surface types of scab to meet U. S. No. 1 standards were 235, 153, 96, 84 and 40 bushels, or 61, 45, 36, 42 and 40 per cent of the respective average totals for 6 of the 7 tests.

Both pitted and surface scab were influenced in the same way by time of planting.

Soil moisture appeared to be an important factor since it influenced both the yield and scab development in these experiments.

The results of these experiments indicate that the earliest possible planting of Irish Cobbler, Katahdin and Sebago is one means of avoiding losses caused by scab in the muck soils of northern Indiana.