The rate and amount of absorption of maleic hydrazide by potato tubers
SummarySebago and Huron potatoes were given a foliar spray of 2500 ppm MH Amine three weeks past full bloom. Sufficient absorption occurred within a 24 hour interval (six ppm residue) to satisfactorily inhibit sprouting of tubers stored six months at 50 F. A more complete inhibition of sprouting was attained following a 48 hour absorption period (17 ppm residue) with the exception of a few tubers with long sprouts which occurred at random. Sprouting was stimulated under conditions of slight absorption (two to four hours and four ppm residue). Residue levels of the Sebago variety continued to increase from six ppm after 24 hours of absorption to a maximum of 36 ppm at the end of seven days, despite very heavy rain on the third and fourth days. Approximately 60 hours were required to attain a 50% level of absorption.
Some effects of maleic hydrazide on stored potatoes
SummaryKatahdin potatoes of different maturities were sprayed with three concentrations of MH and stored under four environments for six months. In the field there were no visible effects on foliage or tubers from any application of MH.Analysis of variance before storage revealed no significant differences in yields, specific gravities, cooked color ratings, and flavor scores.After storage for six months, sprout growth was inversely proportional to the concentration of MH, but proportional to the maturity of the tubers and the storage temperature.The total weight loss of the stored tubers increased with increasing concentration of MH. The weight losses were greatly influenced by the vapor pressure deficits of the storage, and were inversely proportional to the maturity of the tubers.Higher specific gravities resulted from zero and 5000 ppm. concentrations of MH, from immaturity, and from relatively large vapor pressure deficits in the storage atmosphere. Neither the cooked color nor the flavor of the potatoes was affected by MH. Potatoes stored at 32° F. cooked dark and had a sweet flavor.
The Effect of Preharvest Foliar Sprays of Maleic Hydrazide on Sprout Inhibition and Storage Quality of Potatoes.
Field tests were conducted on a productive Hillsdale sandy loam soil using certified seed of the Irish Cobbler and Pontiac varieties planted May 19, 1950, in rows 36 inches apart and with seed pieces at 12-inch intervals. As outlined in table I, single aqueous sprays of 500, 1000, and 2500 parts per million (p.p.m.) of maleic hydrazide were applied to the foliage of the Irish Cobbler variety on July 15, August 2, August 11, or August 19. Plants of the Pontiac variety were treated similarly on July 15, August 2, August 11, or September 2. Treatments were replicated on rows 15 feet in length. Three-gallon hand sprayers were utilized in applying the chemicals and the leaves were sprayed until the solution dripped from the leaves. "Dreft" was added at a concentration of 0.1% as a wetting agent. At the earliest spray application on July 15 (approximately six to seven weeks before harvest) tubers of both varieties ranged from one fourth to two and one half inches in diameter. Forty-eight hours after the latest treating dates, August 19 for Irish Cobbler and September 2 for Pontiac, the vines of all plots were cut off; and the tubers were harvested four days later. Three controls were included to determine the relative merits of the various preharvest foliar sprays of maleic hydrazide (table I) : 1. Successive sprays of 50, 100, and 2O0 p.p.m. of 2,4,5-trichlorophenoxyacetic acid were applied on July 15, August 2, and August 11. This treatment was included because of favorable results reported by Marshall and Smith (10). 2. A post-harvest treatment with the methyl ester of alpha-naphthaleneacetic acid as a dust formulation, "Barsprout" (American Cyanamid Company, New York), was used. Approximately the equivalent of 0.9 gram of the