Optimizing late N applications in durum wheat is highly needed to obtain adequate protein levels without affecting grain yield. A simple and rapid method for estimating crop yield at flowering stage and crop N status is required to make immediate N application decisions for increasing grain protein content. There were significant differences in grain yield and grain protein among N treatments and durum varieties. Using information on soil properties, weather data, crop management, and variety growth, DSSAT crop model predicted durum grain yield accurately. Canopy reflectance index NDVI at flowering time were closely correlated with crop yield and protein content. The results indicate the potential of using crop models and canopy reflectance index in durum wheat yield prediction and N management.

Proposed reduction in maximum allowable cadmium (Cd) level in wheat grain from 0.2 to 0.15 ppm by European Union (EU) could affect Arizona wheat growers substantially. The possible breeding programs and management practices needs to be developed to keep the industry competitive for this major market. In this study, we used two durum wheat cultivars (Ocotillo representing higher Cd genotypes and Havasu representing lower Cd genotypes) to study the potential of Zn fertilizer (as ZnSO₄ and ground tire rubber) to reduce Cd uptake in durum wheat at Yuma Ag Center. While cadmium level in the two varieties were different significantly, applying ZnSO₄ or ground rubber did not affect grain cadmium level, grain yield, or protein content significantly.

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.

During 1990 the emphasis on surveying was placed in the southeastern corner of the state, where damage was found to be most severe in previous years. Estimates of the incidence of and damage caused by the Russian Wheat Aphid (RWA) were made for the entire state. These estimates indicate that small grain producers in the state lost $212,000 due to this pest in 1990.

Yield trials were conducted at the Maricopa Agricultural Center during the 1990 -91 growing season. Barley, Durum and Wheat varieties as well as experimental lines from various seed companies were tested for yield performance. Gustoe and Sunbar 409 barleys, Turbo and Aldura durum wheats; and 911 and Klasic bread wheats were the highest yielding commercial varieties in this yield trial.

Planting date can have a tremendous effect on small grain yield. The purpose of this study is to document the interactions of planting date with current small grain varieties. Field studies were conducted at the Maricopa Agricultural Center over the 198$ 1989, and 1990 growing seasons. Six barley, durum and wheat varieties were compared at four planting dates from November to February. WestBred Gustoe was among the highest yielding barleys and WestBred Turbo was among the highest yielding durum regardless of planting date. The highest yielding wheat was WestBred 911 at the November plantings, Klasic at the December and January plantings, and Topaz and Klasic at the February plantings. The varieties also responded differentially to planting date in terms of plant height, kernel weight, heading and maturity date, but not test weight. This study demonstrates the importance of planting date in choosing a small grain variety.

A 12-inch row spacing is commonly used to evaluate small grain varieties at the Maricopa Agricultural Center and other experiment stations. The objective of this study was to document the interactions of varieties and row spacings. Sir barley, durum, and wheat varieties were planted in the 1989 and 1990 growing seasons at the Maricopa Agricultural Center at four planting dates (November, December, January, February) and 6 and 12-inch row spacings. At the December planting date, which is near optimum, WestBred 881 and Topaz performed best at a 6-inch row spacing while Gustoe, Aldura, Klasic, and WestBred 911 performed best at a 12-inch row spacing. Caution must be exercised when interpreting variety trials planted in 12-inch rows anti, in addition, conducted under growing conditions different from commercial practice.

This experiment was conducted to quantify herbicide carry -over effects on wheat, after plowing the cotton down with conventional and reduced tillage systems. Cotton layby applications of cyanizine, diuron, and prometryne at 1.5 lbs/Ac active ingredient did not result in wheat yields that were significantly different from the untreated checks within any of the tillage systems.