Higher nutrient and water use efficiency are possible with microsprinkler-irrigated citrus compared to flood-irrigated citrus. Therefore, new N and P fertilizer recommendations are needed for microsprinkler-irrigated citrus. The objectives of these experiments were to i) determine the effects of N applications on tree growth, fruit yield, fruit and juice quality, and N and P removal in fruit for microsprinkler-irrigated navel oranges; ii) determine the effects of P applications on tree growth, fruit yield, fruit and juice quality, and N and P removal in fruit, and iii) develop Best Management Practices for N and P fertigation of microsprinkler-irrigated citrus. Field experiments were conducted at the University of Arizona Citrus Agricultural Center in separate blocks of 'Newhall' and 'Fukumoto' navel oranges, both on 'Carrizo' rootstock. In each block, ten treatments, consisting of all possible combinations of 5 N rates (0, 0.2, 0.4, 0.6, and 0.8 lb N/tree/yr) and 2 P rates (0, 0.2 lb P/tree/year) were applied to five replicate trees per treatment. Maximum yields of the ‘Newhall' trees were 132 lb fruit/tree at a N rate of 0.5 lb N/tree/yr. Maximum yield of the 'Fukumoto' trees was119 lb fruit/tree at 0.5 lb N/tree/yr. Both varieties maintained appropriate leaf N and P concentrations at the yield-maximizing N rates. Total N in the fruit accounted for about 60 % of the N applied at the yield-maximizing N rates in both varieties. The results confirmed that microsprinklers effectively reduced the amounts of N fertilizer needed while maintaining adequate N status in the trees, with excellent N use efficiency.

Two small plot efficacy trials were conducted evaluating different insecticide rotation regimes using commercially available insecticides and the effectiveness of new insecticide chemistries to control citrus thrips. Under the consistently cool conditions experienced during the first four weeks of the trial, Dimethoate, Success, Baythroid, Agri-Mek, Vydate and Carzol all of the offered adequate control and would fit well in the petal fall window. This is in contrast with previous years experiences when high temperatures within a week of petal fall would result in all treatments except Carzol requiring a re-treatment within ten days. All of the rotation schemes evaluated required three insecticide applications to get through the season, and did not appear to be greatly different in controlling thrips and producing high quality fruit under the environmental conditions experienced. However, the Dimethoate - Success - Baythroid rotation scheme was most cost effective. When temperatures were in the 70's to low 80's, Dimethoate and Vydate offered about three weeks control, Success, Carzol, Baythroid and Agri-Mek all offered about four weeks control. When temperatures were in the mid to upper 80's and low to mid 90's, Success provided about three weeks control while Carzol didn t require re-treatment for 4 weeks. Under these same temperature conditions, Dimethoate and Vydate gave about 7 to 12 days control, and Agri-Mek provided 12 to 14 days of control. Other than the one control failure with Baythroid, under warmer conditions, it provided about seven days control. In the experimentals test, AZEXP1 appeared to offer knockdown activity at temperatures less than 90 F, and only suppression at higher temperatures. AZEXP2, appeared to be a viable citrus thrips material, with activity similar to Success and Carzol. The knockdown activity of M96 appeared to be enhanced by including Dimethoate or Carzol, but will require multiple applications to achieve the level of repellency experienced in 1997.

Four 'Lisbon' lemon selections, 'Frost Nucellar', 'Corona Foothills', 'Limoneira 8A' and 'Prior' were selected for evaluation on Citrus volkameriana rootstock. 2005-06 results indicate that the 'Limoneira 8A Lisbon' and ‘Corona Foothills Lisbon’ are superior to the other two selections tested.

This experiment was established in January 2000 in a block of ‘Washington’ navel orange trees at Verde Growers, Stanfield, AZ. Treatments included: normal grower practice, winter low biuret (LB) urea application, summer LB urea application, winter LB urea application plus winter and spring potassium phosphite, winter LB urea application plus summer potassium phosphite, and normal grower practice plus spring potassium phosphite. Each treatment was applied to approximately four acres of trees. For 2000-01, yields ranged from 40 to 45 lbs. per tree, and there was no effect of treatments upon total yield, and only slight effect upon fruit size, grade and quality. For 2001-02, there was a slight effect of treatment upon yield as LB urea led to improved yield, while potassium phosphite led to reduced yield. Normal grower practice was intermediate between these two extremes. For 2002-03, we noted a large increase in yield, however the yield data was lost when the block was inadvertently harvested. For 2005, there was no effect of treatments upon total yield.

The effects of the navel orange prorate suspension on packinghouse to retail price spreads are analyzed When compared with price spreads for the 1986 season, F.o.b.-retail price spreads declined for Atlanta and San Francisco, but increased for Dallas.

Much of the citrus produced in southwestern Arizona is grown on sandy soils. Because these soils have a low ion exchange capacity, are highly permeable to water, and are prone to nitrate leaching, achieving efficient N management presents a continuing challenge. Studies were conducted during 1999, 2000, and 2001 to evaluate the response of micro-sprinkler irrigated lemons to N rate (0, 1.8, and 3.6 kg N tree-1 yr-1) and N source (UN32, CAN-17, CN9, and mixed program) on Superstition Sand. Lemon yield increased by N rate during the first and second harvests in 1999, 2000, and 2001. In 1999, yields increased linearly to 3.6 kg N tree-1 yr-1 but in 2000 and 2001 yields were maximized at 1.8 kg N tree-1 yr-1. In 1999 where larger increments of N were applied over a smaller time period relative to the other seasons, UN32 seemed to decrease yields at the highest N rate. There were no significant effects to N source in 2000 and 2001.

Activity under the Arizona Cooperative Citrus Registration- Certification Program was at a new low during 1984 and 1985; no trees were budded under the program during that period. however, increased budding and bud sales during 1986 herald increased activity in the future. Because the program has continued to receive the support of the citrus industry, services have been provided uninterrupted. The program continues to maintain the foundation blocks insuring the industry with sources of budwood that have successfully met all requirements for: 1) freedom from known viruses or virus-like disorders, 2) freedom from injurious pests and diseases, and 3) trueness to horticultural type.

Vivaparity, a significant quality- reducing condition found in pecans grown in warm, temperate climates, was evaluated by location of the pecan nut within the cluster in two varieties, "Wichita " and "Western Schley". Percentage vivaparity was not affected by position.