The Assessment of Economic Losses due to Late Blight of Potato1

The development of a method which reliably estimates the loss for any given level of disease is a prerequisite to the development of a rational disease control program. Such a method was developed between 1953-1970 using results from field experiments; it led to a multiple regression equation in which the yield loss is the dependent variable. The decrease in marketable tubers because of their reduced size was also considered. The method of estimating yield loss due to late blight is currently being used in conjunction with a disease simulator.     

Economic Aspects of Integrated Control1)

Evaluation of economic returns resulting from plant protection measures are receiving increased attention. Since control measures are likely to affect not only a single production but also future crops and may entail resistance phenomena, as well as other inconveniences, the entire lifetime of a control strategy should be considered in a cost/benefit analysis. Although all the needed parameters for such an evaluation are not available, simplified computer-based models, now in use in advanced pest management studies, turned out to beextremely useful. The possibility of assessing the impact of control measures on single crops is reviewed in the light of recent studies (Headley , 1972, 1973, Davidson and Norgaard , 1973) and data stressing the economic advantages of pest management schemes in European orchards and U.S. cotton areas are studied. With increased prices for pesticides and application, the benefit derived from integrated control schemes becomes more evident.     

Delta Gold: A new potato variety with yellow flesh,high solids and high quality for baking and processing

Delta Gold is a medium-late maturing, round, yellowish-skinned, yellow-fleshed variety which is excellent for baking and processing. Its yields have been lower than Kennebec; however, specific gravities have been higher. It is moderately resistant to scab and early blight and immune to net necrosis and virus A.     

Inactivation of trypsin inhibitors in sweet potato and taro tubers during processing

In order to understand the extent of elimination of trypsininhibitors during processing of sweet potato (Ipomoea batatas) andtaro (Colocasia esculenta) tubers, a detailed study was conductedusing tubers processed by oven drying, cooking, and microwavebaking. Between 80 and 90% trypsin inhibitor (TI) activity wasretained in sweet potato chips up to 2h at 70 ^°C. Among thefour cultivars of sweet potatoes, RS-III-2 trypsin inhibitors were more heatlabile. Heating at 100 ^°C led to rapid inactivation of TI of sweetpotatoes. Varietal differences in thermal stability were more pronouncedfor the trypsin inhibitors of taro than sweet potatoes. Taro inhibitors werealso more rapidly inactivated than sweet potato TI. Between 17 and31% TI activity was retained in cooked tuber pieces of sweet potatoes,while only 3–10% were retained in taro cultivars. Very effectiveinactivation of trypsin inhibitors of sweet potatoes and taro could beobtained through microwave baking. Flour prepared from taro was devoidof TI activity, while 5–12% TI activity was retained in the flour preparedfrom sweet potatoes. The study clearly established that among the fourtechniques used, microwave baking and flour preparation were the best methods to eliminate TI from sweet potatoes and taro.