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.
Spatial distribution of root lesion nematodes (Pratylenchus spp.) in a long-term no-till cropping system and their relationship with soil and landscape properties
The Cook Agronomy Farm of Washington State University is a long-term precision agriculture study site. Since 2000, the farm has been in various three-year no-till rotations with winter wheat, spring wheat, and various rotation crops such as barley, canola, peas, lentils, and chickpea. The spatial distribution of root lesion nematodes (Pratylenchus spp.) and their relationships with soil and terrain variables were studied by collecting soil samples at 127 and 124 geo-referenced points in two 12-ha fields during the spring of 2010 and 2011, respectively. Pratylenchus spp. were detected in more than 85% of the sampled locations in both fields. Nematode densities spatially mapped using ArcGIS software occurred in an aggregated pattern. Previous rotation crops had no effect on the spatial distribution. Classification and regression tree analysis (CART) using soil and terrain variables, and nematode density, explained 61 and 34% of the variability associated with nematode density in 2010 and 2011, respectively. Soil edaphic factors, such as organic matter, were stronger predictors of nematode populations than rotation effects.