The Effect of Preharvest Foliar Sprays of Maleic Hydrazide on Sprout Inhibition and Storage Quality of Potatoes

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Abstract
Sprays of 500, 1000 and 2500 ppm. of maleic hydrazide applied to the foliage of Irish Cobbler and Pontiac potato vines approx. 1 to 7 wks. prior to harvest were effective in prolonging dormancy of tubers held in storage for 7 mos. at 45 and 55[degree]F. The inhibition of sprouting resulting from single preharvest foliar sprays of 2500 ppm. of maleic hydrazide applied 4_7 wks. before harvest was more complete than that obtained with preharvest foliar treatments of 2, 4, 5-trichlorophenoxyacetic acid or with post_harvest applns. of the methyl ester of alpha_naphthaleneacetic acid. Maleic hydrazide_ induced sprout inhibition treatments were accompanied by an absence of shriveling with little or no deterioration of quality and with no reduction of yield of U. S. No. 1 potatoes. Apical dominance of both tubers and individual sprouts on the tubers was destroyed. The percentages of reducing and non-reducing sugars were lower in maleic hydrazide_treated potatoes stored at 45[degree]F. The lower content of reducing sugar was evidenced in lighter colored chips. The possible significance of maleic hydrazide for controlling the degradation of starch to sugar in the storage of potatoes at low temps. as well as the inhibition of sprouting at high temps. is discussed.