Nut grass eradication studies. III. The control of nut grass, Cyperus rotundus L., on several soil types by tillage

Eleven cooperative tillage experiments dealing with the eradication of nut grass were conducted on 10 soil types during the growing seasons of 1938 and 1939. The soil types varied from a deep phase of Norfolk sandy loam to Susquehanna very fine sandy loam (having a shallow surface soil and a plastic clay subsoil) and Eutaw clay. Near eradication was obtained by certain tillage treatments on all soil types. Based on tuber counts alone, plowing at intervals of four weeks gave as good results as turning at shorter intervals. When the sprout counts of the final infestation records were taken into consideration, however, it was obvious that plowing at intervals of two or three weeks was more effective. Plowing with a scrape gave results comparable to those obtained with a turn plow. Thus, equipment available on the smallest farming unit can be used successfully to combat nut grass. The disking experiments emphasized the necessity of a suitable disc if this implement is to be used for the control of nut grass. A light, horse-drawn disc was unsatisfactory, but a tractor disc was comparable to a turn plow. The only experiment in which satisfactory control of nut grass was not obtained was one situated on a low, poorly drained area of Eutaw clay. The results indicate that tillage methods should not be used for nut grass control on areas that are likely to remain wet for long periods. The destruction of nut grass by tillage is based on the fact that most of the tubers are located in the upper 6 inches of soil. Tubers isolated by repeated plowing are killed by desiccation and starvation. An occasional tuber below plow depth may live through two successive tillage seasons. These tubers are a source of potential reinfestation. It is believed, however, that any farmer who will plow at regular intervals for two growing seasons to destroy nut grass will complete the eradication of the pest by digging up each tuber as it sprouts the following year. It is concluded that nut grass can be nearly eradicated from soils varying in texture from sandy loam to plastic clay by plowing at intervals of three weeks during two successive growing seasons. If a clean-cultivated crop is planted the following year and if the few remaining tubers are removed as they sprout, the eradication will be complete.