Alternaria fruit rot on Minneola tangelos and navel oranges can reach economically important levels in central Arizona. The objective of this study was to test the efficacy of a new fungicide in development, BAS 500, for disease management. A trial was conducted in a commercial Minneola tangelo grove with a history of Alternaria fruit rot. Within this grove, nine trees were sprayed monthly from August to December 2000 with BAS 500 at a rate of 0.25 lb active ingredient per acre. Another nine trees were not sprayed and served as controls. Disease severity was evaluated monthly from September 2000 to March 2001 by counting the number of infected fruit that had dropped from trees. No disease was evident on fruit from August through November, when fruit were green. By December the fruit had matured and turned color; additionally, the first fruit were detected with Alternaria fruit rot. In December and January there was little difference in the number of infected fruit on treated compared to nontreated trees. On the other hand, by February and March the cumulative number of infected fruit from trees treated with BAS 500 was 3.0 and 3.7 %, respectively, whereas the cumulative number of diseased fruit from nontreated trees during the same months was greater at 4.9 and 6.4 %, respectively. This study will be repeated next year with an adjusted spray schedule with the goal of increasing the level of disease control.

This experiment was initiated in March 2000 to study the feasibility of growing organic lemon in the desert southwest of Arizona. A ten-acre field planted to lemons in 1998 was selected on Superstition sand at the Yuma Mesa Agricultural Research Center. The initial soil test in top 6 inches was 5 parts per million (ppm) NO₃⁻ and 4.9-PPM NaHCO₃⁻-extractable P. Soil pH was 8.7 in the top 6 inches. Seven treatments were applied in randomized complete block design repeated three times. The treatments were control, compost and clover, compost and perfecta, compost and steam, manure and clover, manure and perfecta and manure and steam Leaf tissue analysis indicated that nitrate level was significantly influenced by treatment. Organic insect control treatments for citrus thrips were as equally effective as the non-organic commercial standards.

A small plot trial was conducted to evaluate the benefit of applying insecticides for citrus thrips management pre-petal fall. Because of low thrips densities during the pre-petal period, we were not able to discern tangible benefits from making prepetal applications. However, in situations where fruit is present and petal fall has not fully occurred, these applications may be useful to protect these fruit. Of the acute toxicants evaluated pre-petal fall (Assail and Success), Assail appeared to be the best choice. However, if temperatures are approaching 95°F, Assail should be avoided. Pre-petal fall applications of Surround and Snow are beneficial in respect that several applications of these products may be required to obtain adequate coverage, and by making these applications during the pre-petal fall period, thrips can be managed before many susceptible fruit are present.

Surround WP was evaluated at various spray volumes to determine if volumes lower than the label recommended volume of 250 gallon per acre would provide equivalent citrus thrips control and yield enhancement potential. All the spray volumes evaluated (50, 100, 150, and 250 gpa) appeared to be equally effective. It appears that as long as the spray coverage appears to be visually adequate, then coverage is sufficient. Application of Surround WP led to some increase in fruit size, particularly for the first harvest.

An attempt was made in 1997 to rejuvenate neglected, mature 'Wichita' pecan trees in a commercial Pinal County grove by applying two types of heading back pruning cuts. The treatments were applied during the dormant season prior to the growing season. The trees were pruned using proven horticultural techniques which included dehorning (cutting main scaffolds to within 2 feet of the trunk) and cutting main scaffolds by 50%. After four years of data, the trees receiving no pruning treatments are producing as well or better than trees to which the pruning treatments were applied. The data suggests that a return to normal irrigation and fertilization practices alone will return neglected, water-stressed trees to normal productivity as early as trees that have been headed-back.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Surround WP and Snow were evaluated for their ability to manage citrus thrips populations in lemons on the Yuma Mesa, and their impact on lemon yield, fruit quality, and packout. Both Surround and Snow effectively controlled citrus thrips and prevented fruit scarring. Surround produced higher yields than either Snow or the commercial standard at the first harvest (#9 ring). There were no differences in yield among treatments for the second (strip) harvest, nor were their any differences in total yield. These data suggest that Surround may increase fruit earliness or sizing. There were no statistical differences among any of the treatments in fruit size frequency or quality for any of the harvests, and there was no apparent benefit from applying an additional application of Surround or Snow post thrips season solely for quality, fruit size, or yield enhancement. The activity of Surround does not appear to be adversely affected by the inclusion of the insecticides Danitol, Baythroid, Carzol, or Success, nor do these insecticides appear to be adversely affected by Surround. Foliar fertilizers did not appear to adversely affect the activity of Surround when tank mixed. However, there is some evidence that Surround may negatively affect the absorption of Fe and Mn when tank mixed with Zn, Fe, Mn lignosulfonate, but this data is not conclusive. The addition of a non-ionic surfactant appears to enhance the on-leaf distribution of Surround over light petroleum and paraffin based oils, but long term efficacy is not affected.

Citrus leafminer (CLM) was monitored in a five year old block of lemons on the Yuma Mesa for one year. Unlike 2001, no CLM were found in the spring or early fall. From mid-November through mid-December CLM populations were very light ranging from 1 to 4% infested flush. In early January 2003, the CLM population began to increase peaking on 23 January at 68% infested flush. Although 68% appears to be a large infestation, the CLM population was not numerically high since there was not a great deal of fresh flush growth in the grove at that time. Thus, the CLM were concentrated on what little flush was present. Additionally, CLM larvae were tagged and monitored in January and February 2003. Of the 25 CLM larvae tagged, within five weeks only 9 had survived. Most of those killed appeared to have been killed by predators; most likely Yuma spider mite, Eotetranychus yumensis, and to a lesser extent Tydeus spp. Six of the larvae were killed by parasitoids, comprising two species; Cirrophilus coachellae and an unknown species that was damaged and could not be identified.

Lemons were left untreated or treated for mites with Danitol (fenpropathrin). Mite populations were estimated and yield and fruit damage was accessed. Yuma spider mite, Eotetranychus yumensis, was the predominate mite species present during the high fruit susceptibility period. Although there was no apparent impact of mites on yield in this study, there was significant fruit damage that could be attributed to Yuma spider mite. The damage appeared as bronzed colored pitting of the fruit peel. Based on damage ratings, the treated plots produced 56% fancy, 34% choice, and 10% fruit grade based on mite damage, whereas the untreated plots produced 47%, 31% and 22% fancy, choice and juice grade fruit respectively. Statistically, the treated plots produce more fancy and less juice fruit, but did not differ in choice fruit. Although the treated areas produced better quality fruit, the amount of damage suffered in those plots was higher than desired. Fruit in the treated plots likely suffered some mite damage before treatments were initiated. In addition to the fruit damage test, a miticide efficacy test targeting Yuma spider mite on lemon was conducted comparing Agri-Mek, Danitol, Kelthane, Microthiol, and Nexter to an untreated check. Agri-Mek, Nexter, and Microthiol offered 14 days of control; although at 6 DAT Agri-Mek and Nexter did not differ from the untreated. Danitol and Kelthane contained fewer mite that the untreated for at least 35 DAT.

A study was initiated in the spring of 2003 to evaluate the response of lemons to soil and foliar applied micronutrients for two growing season (2003-2005). Soil applied Fe, Zn, Mn, and Cu was applied in sulfate form and B as Solubor in shallow holes around the skirt of each tree. Foliar applied micronutrients were all applied as “Metalosate” products. Lemon leaf tissue analyses show marginal levels of Zn, Mn, and Cu throughout the study. In 2003-2004, soil fertilization sometimes increased leaf nutrient composition but there was no effect to foliar fertilization. In 2004-2005, ,leaf B and Zn increased to soil fertilization and leaf Mn and Cu increased to foliar fertilization Overall, there were no significant differences in yield or quality to micronutrient fertilization in either growing season.