W. A. Rawlins

Off-flavor of potato tubers produced by benzene hexachloride used for wireworm control

Summary—Samples of potato tubers from experiments conducted for wireworm control were tasted for benzene hexachloride off-flavor. Tubers from soil applications, fertilizer combinations, seed pieces treated with benzene hexachloride, and tubers from check or untreated lots were used in taste tests conducted at three different places. Those who tasted the different samples showed wide variations in their abilities to detect and to determine off-flavor of the tubers. A positive relationship was observed, however, in which samples of potatoes from the higher dosage concentration treatments expressed as pounds of gamma-benzene hexachloride applied per acre were more frequently recorded as off-flavor than those of lower concentrations or of the checks.

The control of potato aphids on long island

SummaryPotato aphids,Macrosiphum solanifolii Ashm. andMyzus persicae Sulz. have frequently infested Long Island potato plantings. The use of nicotine spray and nicotine vapor has given excellent control of potato aphids which has been reflected in increased yields of tubers.For a number of years observations have shown that the potato aphid populations at the peak of infestation are larger on bordeauxsprayed plants than on unsprayed plants. Furthermore bordeaux spraying has in many instances, decreased yields during non-blight years. The increased aphid populations on bordeaux-sprayed plants may account for these decreases in yield.

Some varietal differences in wireworm injury to potatoes

SummaryIn a series of potato variety trials small but significant differences among varieties have been observed. Although all varieties tested were subject to wireworm attack, some varieties appeared to be more susceptible than others.

The interaction of bordeaux mixture spray, sulfur and pyrethrum dusts on potato yields and insect control

In tests previously reported, increased yields of potatoes were obtained in certain experiments in Western New York by increasing the amounts of copper sulfate applied in the form of bordeaux mixture. Maximum yields were obtained by applications of approximately 75 pounds of copper sulfate to the acre during the season. The use of larger amounts of copper sulfate increased foliage growth at the expense of tuber formation. Furthermore, these experiments showed that the application of the larger portion of this optimum amount of 75 pounds in the early part of the season not only gave still greater increases in tuber weights but also a better grade of tubers, as compared with applications of equal amounts of copper to each application or larger amounts in the latter part of the growing season (2). These investigations suggested that the increased yields from bordeaux mixture were not due entirely to its fungicidal and insecticidal properties. In following up this suggestion, experiments were conducted in 1935 and 1936 to determine the comparative effects of applications of bordeaux mixture with and without the application of insecticides designed to control the insects independently of the bordeaux mixture. A summary from all these experiments gives some indication of the effects of these insecticidal dusts both on yields and insect control.

Control of the potato flea beetle with applications of insecticides to the soil

Recent reports have indicated that the potato flea beetle. Epitri.v cucumer&, is increasingly more difficult to control with DDT. This suggests resistance or tolerance, commonly the aftermath of repeated exposures over several generations of an insect species to an insecticide. Loss of the effectiveness of a material in this manner dictates a change to other insecticides of greater potency. In case of the potato flea beetle dieldrin, heptachlor, chlordane and endrin have been proven satisfactory to replace D D T in the spray and dust programs. These insecticides are better known for control of soil insects and in this role they are promising as a means of eliminating flea beetle larvae infesting potato hills. Soil applications are an accepted practice in the potato growing areas of western United States where the potato tuber flea beetle, E. mberis is a serious problem. Larvae of this species feed extensively on the tubers causing small brown flecks in the flesh. The eastern species, cucu~wris, is largely a foliage pest, chewing small holes in the leaf tissue, but occasionally the larvae cause injury to the tubers. Recently. Hofinaster (1) obtained excellent results with soil treatment to control E. cucunwris attacking potatoes in the t~2astern Shore of Virginia. He suggested soil application as an alternate means of controlling the flea beetle, the other method being foliage sprays or dusts. In New York marked decreases in flea beetle infestations have resulted from soil treatments for wireworm control. This has been generally recognized by potato growers and some have been enthusiastic over soil insecticides as a nleans of controlling flea beetles. A soil application aimed solely at flea beetle control would be an additional operation preparatory to planting. The efficiency of such a practice is questioned since foliage applications at the proper times would also achieve adequate control. The insecticides may be added conveniently to the fungicide usually applied at frequent intervals during the growing season. However, it is conceivable that soil treatments might supercede foliage sprays or dusts in the event of beetle resistance to insecticides. This presupposes that the larvae do not acquire the same degree of tolerance as the beetles.

Timing applications for control of potato aphids on Long Island

Potato plantings on Long Island are often heavily infested with several species of aphids, of which the pink and green potato aphid, Macrosiphum solanifolii (Ashm.), and the green peach aphid, Myzus persicae (Sulzer) are most numerous. The aphid problem has become increasingly important during recent years although efforts to control aphids have not always been profitable. Huckett ( I ) was unable to demonstrate yield increases large enough in many seasons to be commensurate with the cost of treatment. However, experiments of recent date (2) have been more encouraging. These experiments have shown considerable benefit from reducing aphid populations. Of further interest to the Long Island grower is information on the number and timing of insecticide applications. This has been the objective of experiments conducted during the past three seasons in both Nassau and Suffolk counties. Difficulties have arisen in proper timing because of markedly fluctuating aphid populations that seemed to defy prediction. PERIOD OF APHID INFESTATION

Further studies on continous cultivation as a control for Wheat Wireworms

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