No description available.

Water and fertilizers are the two major agricultural inputs limiting yields in the arid and semi-arid regions of the world. Proper knowledge of their influence on crops should be obtained for appreciable returns. Therefore, a field study was conducted to evaluate the effects of four nitrogen (N) treatments (0, 56, 112, and 168 kg N/ha), two water (M) levels (39 and 58 cm), and two varieties (V) (Funks G-522DR and Conlee Rusler) on dry matter production, total N concentration, and yield of grain sorghum (Sorghum bicolor (L.) Moench). Total N concentration, dry matter, and grain yield were increased by N treatments. Generally, the highest N rate gave the most significant effects; the other rates had statistically the same responses. Varieties were different in their dry matter and grain yields, but had the same total nitrogen contents, as was suggested by the ANOVA and means analysis. There were no detectable interactions among the factors. Moisture had minimal effect on dry matter and grain yields, but influenced total N concentration significantly. Nitrogen contents increased with the higher moisture level.

No description available.

No description available.

No description available.

Species in the genus Armillaria are Basidiomycete, white-rot fungi. A study was done to determine the speciation of southern Arizona field collections. A number of isolates were positively or tentatively identified as belonging to Armillaria intersterility groups I, III, IV, or X. Some isolates had negative mating reactions with all intersterility group testers. Temperature - growth rate studies were done, and other cultural characteristics described. Additional areas of research on the species of Armillaria in southern Arizona were suggested.

Crude sap of pepper Capsicum frutescens L. 'NM 6-4' infected with pepper mottle virus (PeMV) was treated with nitrous acid to induce mutants. Twelve isolates were selected from two distinct types of local lesions on Capsicum frutescens L. 'tabasco'. Of the twelve isolates, four produced mild symptoms on both pepper foliage and fruit. When these mild isolates were inoculated to pepper plants and subsequently challenged with wild type PeMV, they protected the plants from the severe effect of the wild type isolate. Marketable pepper fruit from these protected plants was not significantly different from fruit from uninfected pepper plants.

A field survey of mature lemon trees showed an average of 30% of the trees with symptoms of brown heartwood rot caused by Coniophora sp. The temperature range of growth in culture for Coniophora is 15-40C with growth optimum at 30C. Vegetative incompatibility trials from one mature orchard show isolates from different trees are incompatible. In wood block decay studies, the average weight loss over 20 weeks was 5-20%. In comparison, decay studies comparing Coniophora with other brown or white rotting fungi, the other fungi decayed 4-8 times more in vitro. Cultural characteristics include simple septate hyphae, moderately growing mycelium that develop crustose brown to brownish-black patches as they mature, and negative for polyphenol oxidases. In vitro fungicide trials show that only NECTEC paste was effective in reducing decay on lemon blocks inoculated 15 weeks with Coniophora. SEM studies show mycelial fragments, pit enlargement, in radial plates, cracking and disintegration of wood.

No description available.

No description available.