Threecornered alfalfa hopper, Spissistilus festinus (Say), is a pest of soybean during vegetative and reproductive stages. The primary damage from this pest is girdling of the main stem during vegetative stages and girdling of the petioles during reproductive stages. Previous research determined that yield losses are greater during reproductive stages than vegetative stages. I hypothesized that some reproductive stages are more vulnerable to damage than other stages. I used field cages infested with different pest densities at five reproductive stages of group IV soybean. A greenhouse study compared the injury and damage caused by the adults and nymphs. The field study showed that the threecornered alfalfa hopper did not significantly impact yields at the growth stages studied. Adults preferred to feed on leaf petioles while nymphs fed mostly on stems. Significant yield reduction was noticed at growth stage R4 in the greenhouse due to adult and nymphs compared to control.

No description available.

No description available.

In our country the necessity to offer new alternatives for the agricultural sector is high-priority especially for the lucern cultivation that every day is surface cultivated especially in the Chimborazo province increases; for what is of our interest to establish the answer from the cultivation to the inorganic fertilization and liming for the flora pH correction, for this way to obtain better yields and for consequence to improve the economic conditions of the farmers. With the result that the titled investigation: Efficiency of the Inorganic Fertilization in the Alfalfa Cultivation (Medicago sativa L) and Liming for the Correction of the pH of the Flora had the following objectives: to determine inorganic fertilization efficiency in the lucern cultivation and liming for the correction of the pH of the floor; to evaluate the production of the lucern cultivation; to carry out an economic analysis.

M. S.

Sclerotinia crown and stem rot (SCSR), caused by Sclerotinia trifoliorum Eriks., causes serious spring losses in some fall=sown, no-tillage alfalfa fields. In microplots artificially infested with sclerotia, greatest numbers of apothecia were found during November and December. Temperature and rainfall had significant impact on apothecium development. A proposed prediction method for apothecium appearance considers monitoring mean soil temperature. For apothecium initiation to occur, it was necessary for sclerotia to be subjected to an estimated 17 days of temperature at or below 15 C before apothecium production occurred. Soil temperatures were usually below 10 C at the time of apothecium appearance. Greatest numbers of apothecia occurred between 5-10 C. Rainfall influenced the number of apothecia, with significant increases occurring early in the 1984-85 production period. / Master of Science

M.S.

No description available.

No description available.

The effects of apholate on diapausing and nondiapausing alfalfa weevil, Hypera postica (Gyllenhal), were studied. Different stages, sexes, and ages of the weevil were treated with aqueous-apholate solution. Adult topical application and larval and adult dipping methods were used in the experiment. Both showed the effectiveness of sterilization, and caused high mortality to the treated insects. Adult dipping was an acceptable method of treatment. The best age for treatment seemed to be reproductively mature virgin adults. Egg viability was similar to the check when only the females were treated with apholate. When only males or when both sexes were treated the egg viability was decreased depending on the apholate concentration used. The most effective apholate concentration for sterilizing male alfalfa weevils ranged from 0.5 to 1.0%. A gradual increase in egg viability occurred starting about the 3rd week after treatment. Dissection of the immature adults showed that gonadal development was delayed by apholate. The reproductive organs of apholate-treated mature adults were reduced in size. The treated males do not compete sexually on an equal basis with the normal males, although considerable mixing of sperm occurred during the mating of female weevils with the apholate-treated and -untreated males. / M.S.