A field experiment was conducted in 1998 to determine the efficacy of Puma and Hoelon for littleseed canarygrass control in durum wheat. The herbicide treatments consisted of three rates of Puma, 0.83, 1.24, and 1.66 oz a.i./A, and one rate of Hoelon, 6.8 oz a.i./A, that were applied at two application timings. The early-postemergence (EPOST) applications when canarygrass had 2.2 leaves per plant did not result in commercially acceptable control due to water stress. Increasing rates of Puma applied mid-postemergence (MPOST) when canarygrass had 5 leaves per plant provided increasing canarygrass control (70 to 90 %) with the two higher rates of Puma providing commercially acceptable control. The two highest rates of Puma also resulted in better weed control than the commercial standard, Hoelon, which did not provide commercially acceptable weed control. No herbicide injury symptoms were observed on the wheat at any of the evaluation dates. Grain yield also increased as the rate of Puma applied MPOST increased and yields overall reflected the degree of weed control observed earlier in the season. These data indicate that the combination of Puma applications that killed or stunted emerged canarygrass combined with later season crop competition that suppressed stunted and later emerging canarygrass plants was sufficient to protect grain yields. The highest yielding Puma treatment was equivalent to 4150 lb/A compared to the Hoelon and control treatments which yielded the equivalent of 2753 and 1946 lb/A, respectively.

No description available.

Results from 1988 show that yields of 3.9 and 3.7 tons per acre are feasible for Gustoe and NKX -1558 barley cultivars. The short season cultivar Barcott yielded about one ton less. The predicted optimum amounts of water and nitrogen were approximately 30 inches and 150 pounds per acre, respectively.

One-irrigation barleys were bred to be grown with only a single irrigation near planting time. To further our understanding of how to manage these new cultivars, two one - irrigation barley genotypes (Seco and 2 -22 -9) were grown at four seeding rates (20, 40, 60, and 80 lbs seed /A); four nitrogen rates (0, 50, 100, and 150 lbs N /A); two phosphorus rates (0 and 100 lbs P₂O₅ /A); four row spacings (6, 12, 18, and 24 inch); and three planting dates (Nov 19, Dec. 23, and Jan. 22). The optimum seeding rate, fertilizer rate, and row spacing were dependent on genotype and planting date. The optimum seeding rate was 40 to 60 lbs /A for Seco and 80 lbs /A for 2 -22 -9. An increase in seeding rate decreased kernel weight and kernel number per head but increased head number. A positive response to nitrogen fertilizer was not obtained due to the high levels of residual soil nitrogen at planting (20 ppm NO₃⁻N) except for the case of Seco at the Dec. 23 planting date. Phosphorus fertilizer increased yield only at the Nov. 19 planting date and if accompanied by 100 lbs N /A. Soil phosphorous levels were 2 ppm PO₄⁻P and a positive response was expected Kernel weight was not influenced by Nor P fertilizer. Kernel number per head increased with certain combinations of genotype and planting date. Head number decreased with N rate but increased with phosphorus. The optimum row spacing was 18 inches at the Nov. 19 planting and 12 inches for Seco at the Jan. 22 planting date. At other combinations of genotype and planting date, no differences in grain yield were detected due to row spacing. Kernel weight increased with row spacing at the Nov. 19 planting date; kernel number per head was generally not affected and, head number decreased with row spacing. The results of this study surest that any recommendations on how to grow one - irrigation barley are gross approximations because of variations due to year, planting date, and genotype.

WestBred 881 durum commands a premium price due to its superior quality, but it produces a lower yield than other commonly grown cultivars. This study was initiated to improve our understanding of how to grow WestBred 881. Two dumm cultivars (WestBred 881 and Aldura) were planted at five seeding rates (30, 60, 120, 180, and 240 lbs seed /A) and five row spacings (3, 6, 12, 18 an 24 inches) at the Marana Agricultural Center. The optimum seeding rate was 180 lbs /A for WestBred 881 and 120 lb /A for Aldura. An increase in seeding rate resulted in decreased kernel weight and number and increased head number. At row spacings of 3, 6 and 12 inches, grain yield of WestBred 881 was 6120, 6300, and 6060 lbs /A and grain yield of Aldura was 6350, 6770, and 7190 lb /A, respectively. WestBred 881 has larger kernels than Aldura but fewer kernels per head and heads per unit area. The yield advantage of WestBred 881 relative to Aldura at higher seeding rates was due to in kernels per head. At the closer row spacings, the advantage was due to kernel weight, kernels per head and heads per unit area.

Three varieties of feed wheat were compared in an on farm demonstration in the Safford valley. AC79 -97, developed by the University of Arizona for the Safford area,produced the largest amount of high protein feed Comparing 200 and 300 pound per acre seeding rates, both AC79 -97 and Super -X yielded slightly more grain at the 200 pound rate than at the 300 pound rate. Yolo, a feed wheat variety that has done well in the Sacramento valley in California, yielded slightly lower than the Super-X.

Plant growth regulators are applied to small grains to decrease lodging which can adversely affect crop growth and yield. Wheat is intensively managed in Arizona, and lodging can be a problem. Chlormequat and ethephon were applied at various rates and times in six studies in 1987 to evaluate their use on Arizona's semi -dwarf cultivars with respect to lodging plant height, yield components and grain yield The results indicated that growth regulators applied at the recommended rates and times may decrease plant height and decrease kernel weight. However, the influence of growth regulator treatments on tiller number, head number, kernel number, and grain yield was not demonstrated. The ambiguous results obtained suggest our efforts need to be directed toward documenting the extent of lodging in the state, studying the effects of lodging and predicting when lodging will occur.

Fifteen small grain fields, including eight wheat fields, two barley fields and five oat fields, throughout the grain growing areas of Graham, Greenlee and Cochise counties were surveyed weekly from the third week in March through the second week in June, to document the presence of Russian wheat aphid (RWA), other aphid, parasites and predators. RWA were found in all three counties and in all three grains. Presence of RWA caused chemical pest control applications in approximately 19%, 33% and 90% of the small grain fields in Graham, Greenlee and Cochise counties, respectively. Thirty three percent of the fields had beneficial parasites and predators were found 93% of the fields. Presence of parasites reduced the RWA populations in 80% of the cases and presence of predators had a dramatic effect on other aphids and was felt to be beneficial in controlling RWA.

Planting date is an important consideration when growing small grain varieties under reduced water use conditions. The objective of this study is to document interactions of planting date and varieties grown with a single irrigation near planting. Field studies were conducted at the Maricopa Agricultural Center during the 1988, 1989, and 1990 growing seasons. Six barley, durum, and wheat varieties were compared at four planting dates from November to February. Early November or early December planting dates were optimum. The relative performance of the varieties differed depending on the year and planting date. The highest yielding varieties over most planting dates were Solum and 6-39-1-1 (barleys), Mexicali (durum), and B85-277A and M83-39-18 (wheats). Improvement of barley, durum, and wheat genotypes for reduced water use conditions continues at the University of Arizona, and notable progress in durum and wheat performance has been achieved recently.

Barley lines have been developed for one-irrigation conditions. The purpose of these studies is to provide information required to develop recommendations for nitrogen fertilizer practices for one - irrigation barley. A total of nine field studies were conducted at the Marana and Maricopa Agricultural Centers testing six nitrogen rates ranging from 0 to 200 lbs N/A under a variety of conditions. The optimum nitrogen fertilizer rate ranged from 0 to 40 lbs N /A. No relationship was established between optimum nitrogen fertilizer rate and preplant soil nitrate, previous crop, planting date, or number of irrigations (1 vs. 2). Based on the results of this and other studies, a nitrogen rate of 40 to 50 lbs N/A is usually adequate for one-irrigation barley, and nitrogen rates greater than 80 to 100 lbs N/A is considered excessive.