Powdery mildew of cantaloupe in Arizona is caused by the plant pathogenic fungus Sphaerotheca fuliginea. The disease is usually found in some melon fields each year; however, the incidence and severity of the disease is quite variable. Disease development is favored by low relative humidity, moderate temperatures, and succulent plant growth. Potential new fungicides were evaluated for disease control in a field trial conducted in the spring of 1993. All tested materials provided significant control when compared to untreated cantaloupe plants. In this study, none of the compounds provided disease protection significantly superior to that demonstrated by Bayleton, the fungicide currently registered for use on cantaloupes.

Foliar insecticides for whiteflies (Bemisia sp., WF) were applied as a supplementary control measure at 6 weeks after treatment with imidacloprid (Admire®) at planting time of melons. Beauveria bassiana fungus spores (Mycotrol®), pyriproxyfen (S-71639, Valent), and azadirachtin (Align®) are non-conventional insecticides that could be safer on beneficial parasites and predators. The number of eggs and nymphs counted at all rating dates for all treatments were not significantly different from the foliarly untreated check. Mycotrol treated melons showed higher number of nymphs following the second application. The Align treatment tended to exhibit higher number of nymphs after two applications. The addition of an adjuvant did not appear to enhance pyriproxyfen efficacy.

Several registered and exploratory herbicides were effective for broadleaved weed control when applied preplant incorporated or preemergence in cantaloupes. Bensulide (Preface), clomazone (Command®), cyanazine (Bladex®), dimethanamid (Frontier®), ethafluralin (Curbit®), metolachlor (Dual ®), pendimethalin (Prowl®), trifluralin, dithiopyr (Rohm and Haas), and thiazopyr (Rohm and Haas) gave marginally acceptable control of most weeds. Crop injury was observed for some treatments of Frontier, Prowl, napropamide (Devrinol®), and Command. As the season progressed, groundcherry (Physalis wrightii) was not adequately controlled by any treatment.

Powdery mildew of cantaloupe and other melons in Arizona is caused by the plant pathogenic fungus Sphaerotheca fuliginea. The disease is found in melon fields each year; however, the incidence and severity of the disease is quite variable. Disease development is favored by low relative humidity, moderate temperatures, and succulent plant growth. Potential new fungicides were evaluated for disease management in a field trial conducted in the spring of 1995. In this study, BAS-490 and Reach provided the highest level of efficacy among the materials and rates tested. Generally, lower levels of disease led to increased yield of marketable fruit.

Beauveria bassiana is a naturally occurring fungal disease of insects that has been shown to be an effective biological control against whiteflies in cotton and vegetable crops. Six treatments were initiated in drip irrigated fall cantaloupe on October 2, and repeated on October 9 and 23. The six treatments consisted of 1) a check or unsprayed plot; 2) 0.5 lb. Mycotrol WP/acre; 3) 1 Ib. Mycotrol WP /acre; 4) 1 pt. Mycotrol ES/acre; 5) 0.5 lb. Mycotrol WP /acre + pyrethroid tank mix; and 6) 12 oz. Naturalis-L/acre. Under moderate to light sweetpotato whitefly pressure, the Mycotrol formulations provided significant control (68-79%) compared to unsprayed check plots, and were superior to Naturalis-L formulation whose effects were relatively short lived. Mycotrol WP applied in three applications at the labeled rate of 1 lb. product/acre had the cumulative effect of maintaining adult whitefly leaf counts below the currently recommended economic threshold of 3 per leaf at 28 days after treatment initiation, under the conditions of this study.

Several experimental insecticide treatment combinations were evaluated and demonstrated very good efficacy against Bemisia argentifolii [silverleaf whitefly (WF) also known as sweetpotato WF, B. tabaci]. Adults and immatures were most effectively reduced compared to the untreated check by pyriproxyfen (S-71639, Valent) treatments and fenpropathrin (Danitol®) plus acephate (Orthene®). CGA-215944 (Ciba) plus fenoxycarb (Ciba) treatments compared favorably with many of the pyrethroid combination treatments. Registered products esfenvalerate (Asana®), endosulfan (Thiodan®), cypermethrin (Ammo®), naled (Dibrom®), and oxydemeton-methyl (Metasystox-R®) complemented many of the combination treatments to reduce WF relative to the untreated check

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Powdery mildew of cantaloupe, caused by the plant pathogenic fungus Sphaerotheca fuliginea, is usually found in some melon fields every year. Disease development is favored by low relative humidity, moderate temperatures, and succulent plant growth. In the spring of 1990, potential new fungicides were evaluated for disease control in a field trial All tested materials provided significant control when compared to untreated plants. Bayleton is the only tested material that is currently registered for use on cantaloupe for control of powdery mildew.

A range of population levels of sweet potato whitefly, Bemisia tabaci Gennadius was evaluated in three field experiments allowing measurement of the effect of whitefly numbers on melon quality and yield. An increase in total numbers of immature whitefly was associated with significant declines in harvested melon weight, a decline in number of boxes harvested, a decrease in fruit size, a decrease in percent sugars, and an increase in sooty mold. Regression analysis of individual whitefly life stages with yield parameters indicated that adult number was a more precise parameter and higher R2 values were obtained with increased range of whitefly population densities. Adults were sampled at the third leaf node in both locations. Nymph samples were taken at varying nodes from the base of the plant. Estimates of the mean adult whitefly density resulting in 5% and 15 % dollar yield loss were 3 and 10 adults per leaf Estimates of the mean total nymph density resulting in 5% and 15% dollar yield loss 0.5 and 2 (AZ) nymphs per cm² of leaf area, respectively.

A range of action thresholds for the control of sweet potato whitefly, Bemisia tabaci Gennadius were evaluated in field experiments with high population density of B. tabaci. Action thresholds for whitefly adults, based on seasonal whitefly averages that could result in 5% and 15 % dollar losses, of 3 and 10 adults per leaf, respectively, were tested. All thresholds were compared to weekly insecticide treatments and an untreated check The resulting best threshold treatment was 3 adults per leaf area which provided a 170% increase in net return over the untreated check. The 3 adult per leaf threshold resulted in 6 applications of insecticide, compared with 10 applications used in the weekly regime.