Three 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. Because of its long residual activity, and ability to control post- application egg hatches, Carzol appears to be the product that best fits the petal fall application window. Agri-Mek, Baythroid, Dimethoate or Vydate are probably good follow -up insecticides. However, Agri-Mek and Baythroid will probably provide greater control, especially under hotter conditions. If temperatures are cool, Agri-Mek looks good at reduced rates. The best insecticide for subsequent applications depends on temperatures and what was previously applied. Avoid making back -to -back applications of the same materials, and Dimethoate or Vydate applications should probably be followed by Carzol to catch post- application egg hatches. Overall, Vydate appears to be very similar to Dimethoate in efficacy and residual activity, while Baythroid appears to be slightly better. Although the addition of Lannate to Dimethoate does slightly enhance thrips control, the additional cost probably does not justify the tank mix. Of the new chemistries (Alert, Success, Ni-25, and M-96-015) evaluated, Success and M-96-015 appeared to offer the best fruit protection. However, M-96-015 does not appear to be very effective in killing the thrips, but is very effective in repelling them. Also, M-96-015 will need to be applied at a high gallonage, i.e. 500 gal/A. None of the new products tested appear to fit the petal fall application window very well. Ni-25, Alert and Success appear to lack the residual activity of Carzol, and M-96-015 should not be used as a clean-up material but preventively following Carzol at petal fall.

M-96-015 did not appear to effectively control woolly whitefly but does appear to kill citrus mealybug. However, as with other insecticides coverage is a problem. The real benefit of M-96-015 towards citrus mealybug would occur if it prevented their spread. However, we were not able to measure this in this study. As with previous trials, M-96-015 is an effective citrus thrips material.

Lemons appear to be most susceptible to damage by citrus thrips from petal fall until they reach 1.0 inch in diameter. Correlation analysis suggests that fruit greater than 1.0 inch in diameter may not be highly susceptible to thrips scarring and thus may not require protection. 1f this relationship can be verged with additional data, late- season thrips sprays may be avoided.

Septoria leaf spot was detected in the United States for the first time in 1964 within an experimental pistachio planting at Brownwood, Texas. The first observation of the same disease in Arizona pistachio trees did not occur until 1986. In 1988, a survey of the 2,000 acres of pistachio orchards in southeastern Arizona revealed a widespread incidence of the disease. Since the initial discovery of the disease, Septoria leaf spot has appeared annually in some of the Arizona pistachio acreage. The onset and severity of the disease is influenced by summer rainfall that occurs in this region. Disease management trials conducted since 1992 have shown that as few as two applications of chlorothalonil in July and August can virtually prevent disease development. Applications of copper hydroxide or benomyl alone or in combination also effectively arrest disease development. Leaves around nut clusters on infected trees not receiving fungicide treatments were usually senescent at crop maturity, whereas leaves on treated trees showed no sign of senescence. Pistachio trees infected with Septoria leaf spot and not treated with an effective fungicide can defoliate in the autumn up to 2 months prematurely.

The life history of the citrus peel miner was investigated. The peel miner larvae were found in low levels in grapefruit throughout the summer. In September the infestation level rose to 10%. Peel miners were also found in oleanders, mesquites, grapes and tree cottons. Peel miners were found to infest at higher levels in the skirt of the tree (less than 32. A parasitic wasp of the larval stage was discovered

New chemistries (Alert, Success, Fipronil, Ni -25, Nexter, Danitol and Baythroid) were evaluated and compared with standard chemistries (Agri-Mek, Dimethoate and Carzol) for control of citrus thrips in lemons grown in the Yuma area. Additionally, Success was compared to Carzol in a large plot commercial demonstration. Under cool, early season conditions, all products appeared to offered good thrips control. However, under warmer conditions, Nexter, Danitol, Baythroid and Dimethoate appear weak. Among the new insecticides, Success and Fipronil appear most efficacious. Alert also appeared to have good activity at the high rate, but appeared to offer shorter residual control than Fipronil or Success. Fipronil was the only new product tested that flared mites. However, rotating sulfur into the Fipronil applications appeared to help prevent flaring. Growers can expect Baythroid and Danitol to behave similarly to Dimethoate for efficacy and residual control. Under commercial conditions, Success provided thrips control equivalent to Carzol at 1.38 lbs-ai/A.

Insecticides were evaluated for their efficacy to citrus mealybugs on lemons at three spray gallonages, 60, 240, and 600 gallons per acre. None of the products tested exhibited any activity at 60 or 240 gallons per acre. At 600 gallons per acre, Lorsban at 6 qt/A + NR-415 oil at 1.4% v/v, Supracide at 2 pt /100 gal + Kinetic at 0.25% v/v, and Applaud at 2.0 lbs -ai/A + NR -415 oil at 1.4% v/v all demonstrated the best activity. Provado at 0.1 lbs-ai/A + NR-415 oil at 1.4 %, Danitol at 0.4 lbs-ai/A + Lorsban at 4 qt/A + NR-415 oil at 1.4% v/v, and Nexter at 0.3 lbs-ai/A + NR-415 oil at 1.4% v/v showed good activity. Weaker treatments included Agri-Mek at 10 and 20 oz/A, Knack and Difenolan. For maximum control, growers should treat before the fruit is heavily infested, and use high gallonages of spray solution at a high pressure, the spray must penetrate the waxy coating to achieve activity. If applicable, a spray oil should be included to help break up the wax. However, if Supracide is used, use a high rate without oil.

The effect of Roundup on lemon trees was evaluated by repeatedly spraying 0.5, 0.75, 1, 1.25, and 1.5 lb. a.i./acre on the bottom 20 to 24 inches of the tree canopies over a three year period. The Roundup applications caused significant leaf injury in the sprayed area of the canopies and there was also significant defoliation of branches at the higher Roundup rates in all three years of the study. In 1996, flower and fruitlet counts were not affected by the Roundup applications and the 1998 data were inconclusive. However, flower and fruitlet counts in 1997 in the sprayed zone of the canopy were significantly reduced by Roundup and the effect increased with increasing Roundup rate. The 1996 and 1997 yield data indicated that Roundup applied to the bottom 20 to 24 inches of the tree canopies did not significantly affect lemon yield. The preliminary data suggest that accidental drift or misapplication of Roundup on to lemon trees when spraying weeds on the orchard floor has no short-term effect on grove productivity.

The fungicide, benomyl (Benlate) was foliar applied by a commercial air blast sprayer at the rate of 1.0 lb. a.i. per acre in early to late August. Treatments varied with a number of applications i.e. one or two and were compared to an untreated control. Benomyl significantly reduced leaf necrosis surrounding nut clusters and the number of leaf spot lesions when compared to control. One or two applications were equally effective in controlling Septoria leaf spot.

The residual activity of insecticides to second instar citrus thrips was measured on lemon foliage in 1998. In April, Dimethoate and Agri-Mek provided only knockdown control of thrips, dropping to <70% mortality by 3 days after treatment (DAT). Baythroid performed slightly better, providing 95% mortality 3 DAT, but by 7 DAT was giving about 74% mortality. Alert, Carzol, Success and AZEXP-2 provided the longest residual activity, lasting 7 days, but began to slip at 14 DAT. AZEXP-1 induced only 74% 0 DAT. Although, residual activity in general was greater in June than April, however this increase in residual activity did not necessarily increase the length of commercially acceptable residual. Agri-Mek and Dimethoate still only provided knockdown activity, and Baythroid was still giving 3 days of good activity. AZEXP-1 performed much better following the June application relative to the April application, providing 3 days of adequate activity. Although we are not certain the reason for this result, it maybe due to the adsorption properties of this chemical relative to leaf physiology. Alert performed similarly in June and April, and Carzol, Success and AZEXP-2 each lasted about 1 week longer.