The squash leaf curl virus (SLCV), transmitted by the sweet potato whitefly (Bemesia tabaci biotype B), is widespread on fall-planted watermelon in the Rio Grande Valley and Coastal Bend areas of south Texas. The objective of the study was to evaluate colored mulches for their effects on whitefly populations, virus incidence, and watermelon yield. Eleven polyethylene films were included as treatments in both a spring and fall study and were replicated five times in a randomized block design. Plastic mulches caused substantial improvement in melon yields (40%) in the spring crop, similar to responses obtained in other studies on cantaloupes. Fall yield increases due to the use of mulches did not occur. Whitefly populations were much lower in 1996 than they have been in previous years, therefore this was not an adequate test of its effects on whitefly behavior. Even so, there were indications in the fall crop that the use of plastic mulch tended to result in lower whitefly numbers. No evidence was found of any difference between the various mulch materials regarding whitefly counts.
Halosulfuron (Sandea 75WG) is labeled for pre- or posttransplant use in tomato, cucumber, cantaloupe, among other vegetable crops. For pretransplant usage, the label specifies a 7-day waiting period after halosulfuron application under the plastic mulch before transplanting tomatoes. This period may be too long for growers who are busy in the spring with planting and pesticide sprays while on a race with the constantly changing climate of early spring. Experiments were conducted in the last 2 years to determine whether transplanting tomato within 7 days of halosulfuron application had any deleterious effects on tomato. In 2003, tomatoes were transplanted daily from day 0 through 7. Plant survival and height were collected. Tomato plants survived all dates of transplanting treatments. Plant height indicated that plants transplanted early were taller than those transplanted late, only because they had more time to establish and grow in the field. There was no adverse effect to tomato growth. In 2004, tomatoes were set on a 2-day interval from day 0 through 10 after halosulfuron application under the plastic mulch. Plant height, visual rating, % early blight infection, and yields were collected. A severe early blight infection confounded the results of herbicide applications. Still, it was clear that halosulfuron 0.026 or 0.051 kg a.i./ha had no effect on plant height or visual rating. Yields were not statistically different from those of the control, when the effect of early blight was factored out.
Races 1 and 2 of Podosphaera xanthii (syn. Sphaerotheca fuliginea) were defined in Imperial Valley, Calif. 1938 when P. xanthii overcame genetic resistance in `PMR 45'. Race 3 was first observed in the U.S. in 1976 in Texas; 15 additional races of P. xanthii have been reported in the literature since 1996. Races 1 and 2 have been common in Arizona and California based upon the effectiveness of the powdery mildew resistance genes in commercially available melon cultivars grown in these states. Field data from 11 commonly used melon P. xanthii race differentials in 2001 and 2002 indicated the presence of race 1 in the Imperial Valley and San Joaquin Valley of California, and Yuma, Arizona. In spring 2003, the powdery mildew race situation changed. The first evidence was the occurrence of a severe and widespread infection of powdery mildew in a commercial cantaloupe field. The 11 powdery mildew race differentials were susceptible to powdery mildew in a nearby replicated field test. PI 313970, a melon from India, was resistant to this apparent new race of powdery mildew.
Bemisia argentifolii is a major pest of melon crop in key production areas of Mexico. Foliar applications of chemical insecticides for their management have been ineffective. The purpose of this research was to evaluate the use of commercial formulations of Beauveria bassiana and different rates for biological control of silverleaf whitefly in cantaloupe melon grown under tropical conditions. Experimental plots were treated with three rates of Mycotrol ES and only an of Naturalis-L or Endosulfan as conventional insecticide. Treatments were arranged in a randomized complete-block design with four replicates. Effects of the treatments on B. argentifolii larval and adult populations and the amount of damage to the foliage and yield melon were recorded. There was not a significant difference between Mycotrol ES rates in nymphs and adults killed. Mycotrol ES, Naturalis and Endosulfan have a similar effect on nymphs and adults control. The nontreated control melon plants had significantly greater number of silverleaf whitefly nymphs and adults than Mycotrol ES, Naturalis-L and Endosulfan treatments. Also, marketable yield was lower for the nontreated control melon plants due to higher whitefly infestations. Results from this study indicate that B. bassiana use resulted in consistently lower whitefly infestations compared to the control. The field results are promising and confirmed the potential of B. bassiana as a microbial control agent against B. argentifolii in melon crop under tropical conditions.
Mini watermelons are the size of cantaloupes and weigh 1.5 to 3 kg (4 to 8 lbs). Melons of 18 selections were grown in replicated trials in North Carolina, South Carolina, and north and south Florida. Melons were harvested when ripe, and samples of heart and locule tissue were frozen and sent to Lane, Okla. A total of 960 samples, representing 6-12 melons per selection per location, were analyzed for total lycopene content using colorimeter and spectrophotometer methods. Subsamples of `Mohican', `Hazera 6007', `Vanessa', `Petite Treat', and `Precious Petite' were analyzed by HPLC for carotenoid profiles. Total lycopene content ranged from 52 to 108 μg·g-1, depending on variety. Selections were grouped into two levels of lycopene content. The varieties Precious Petite, Petite Perfection, Betsy, Bonny, Petite Treat, Valdoria, Vanessa, Hazera 5133 and 5138, RWT 8149, 8155, 8162 had 60 to 79 μg·g-1 lycopene and the varieties Hazera 6007, 5123, 5109, 5177, Mohican, and Extazy had 80 to 100 μg·g-1. Melons harvested from the Florida locations had more total lycopene than those from North and South Carolina. `Precious Petite' had more β-carotene as a percentage of total carotenoids than other varieties tested. These results indicate that lycopene content is affected primarily by germplasm and also by environment.
Muskmelon (Cucumis melo L. reticulatus group), commonly called cantaloupe by growers, shippers, and consumers is a relatively minor crop in the southeastern U.S. The principal restraint on increased muskmelon production in this area is the lack of varieties that consistently produce high quality fruit. Resistance to both fruit rots, especially those induced by Fusarium, and foliar diseases such as downy mildew, powdery mildew, and gummy stem blight are also important because of the high humidity and frequent rainfall common to this area. The ideal shipping variety should have the capacity to produce high yields of round to oval, sutureless, heavily netted fruit that average 1.4 kg each, and that have a deep salmon-colored flesh, a small tight seed cavity, high soluble solids, and a pleasant taste and aroma. Evaluations at Leesburg and Bradenton, Florida over a three-year period have identified several western-type muskmelons well-adapted to this area. `Explorer', `Goldmark', `Mission', and `Tasty Sweet' ranked high in most of the categories mentioned above and should be evaluated in more extensive trials, which should include a study of postharvest quality.
Within a program determining the response of melon plants when grown at suboptimal cold temperatures, fruit quality was examined in 20 cultigens grown under two temperature regimes. The cultigens included open pollinated and hybrid cantaloupes and honey dews. The two temperature regimes were: (i) heated greenhouse, at minimum and maximum temperatures close to commercial cultivation requirements, and (ii) unheated greenhouse, at a temperature 7-8°C lower than the former, representing a major cold stress. The parameters examined included fruit appearance and marketability (weight, size, netting) as well as fruit constituents (sucrose, glucose, reducing sugars, TSS, pH, EC, titratable acidity). Cold stress was found to improve some parameters, but impair others. The low temperatures significantly reduced fruit weight and size, but increased fruit number per plant, sucrose and TSS in most but not all cultigens. Significant interaction was found between the temperature regimes and cultigens in these parameters. The results strongly indicate that genetic variation exists in melons for response to low temperature, and therefore that potential for breeding melons for cold stress is present.
Modified atmosphere packaging (MAP) is a technology that is currently used for most packaged salads and fresh-cut vegetables, and to a lesser extent, fresh-cut fruit such as cantaloupe (Cucumis melo L.), pineapple [Ananas comosus L. (Merr.)], and apple (Malus ×domestica Borkh.). In addition, about 750 million lb (340,200 Mg) of strawberries (Fragaria ×ananassa Duch.), raspberries (Rubus idaeus L.) and sweet cherries (Prunus avium L.) are distributed in MAP annually. The fresh produce packaging industry has developed new films to respond to increased produce consumption and changes in the use of film packaging within different produce marketing segments. The produce film industry sold 60 million lb (27,200 Mg) of film in 1994, and in 2000 it is forecasted to sell 110 million lb (49,900 Mg), an increase of 83%. The distribution of film usage has also changed since 1994 when film consumption patterns were as follows: 20% [12 million lb (5,400 Mg)] retail, 15% [9 million lb (4,100 Mg)] warehouse clubstores, and 65% [39 million lb (17,700 Mg)] food service. In 2000 it is projected that consumption patterns will be as follows: 25% [27.5 million lb (12,500 Mg)] retail, 20% [22 million lb (10,000 Mg)] warehouse clubstores, and 55% [60.5 million lb (27,400 Mg)] food service. These changes represent a 10% shift in film market segment usage patterns away from food service applications to an increase of 5% for each of the retail and warehouse clubstore segments.
A study was conducted in subtropical south Texas in 1989 to determine the effects of planting method, polyethylene mulch, and rate of drip irrigation on cantaloupe growth, yield and quality. Irrigation at .25, .50, .75, 1.0, or 1.25 times pan evaporation had little effect on soil moisture or yield, with all water application levels keeping the soil close to field capacity. Transplanting vs. direct seeding enhanced early vine growth and caused earlier yield, although direct seeded plants later caught up and had final cumulative yields slightly higher than the transplants. Black polyethylene mulch also improved earliness and reduced the number of culls compared to bare soil, but at the lowest watering level total yields were reduced by the mulch due to deflection of the rainfall received. The combined practices of transplanting and polyethylene mulch caused approximately a 9 day earliness advantage over the treatment that was direct seeded on bare soil although final yield was unaffected. Soil salinity buildup may cause problems which would affect the position of the drip line and the frequency and amount of water applied.
A study was conducted in subtropical south Texas in 1989 to determine the effects of planting method, polyethylene mulch, and rate of drip irrigation on cantaloupe growth, yield and quality. Irrigation at .25, .50, .75, 1.0, or 1.25 times pan evaporation had little effect on soil moisture or yield, with all water application levels keeping the soil close to field capacity. Transplanting vs. direct seeding enhanced early vine growth and caused earlier yield, although direct seeded plants later caught up and had final cumulative yields slightly higher than the transplants. Black polyethylene mulch also improved earliness and reduced the number of culls compared to bare soil, but at the lowest watering level total yields were reduced by the mulch due to deflection of the rainfall received. The combined practices of transplanting and polyethylene mulch caused approximately a 9 day earliness advantage over the treatment that was direct seeded on bare soil although final yield was unaffected. Soil salinity buildup may cause problems which would affect the position of the drip line and the frequency and amount of water applied.