In the past we have assumed that sweet potato whiteflies, Bemisia tabaci (Gennadius), were poor fliers with a limited ability to disperse. This assumption was based on the fact that sweet potato whiteflies are extremely small insects (24 -44 μg) and consequently would be subject to desiccation. We also thought small size would limit their capacity to store sufficient energy reserves to sustain flight for long periods of time. Recent experiments have indicated we were wrong on several counts. Data collected in the laboratory using a vertical flight chamber have revealed a number of interesting facts. Of importance is the fact that a portion of the population is capable of sustaining flight for more than 2.5 hours. In a wind-aided situation, this means they can be moved more than 25 miles in a 10 mph wind. Other details of flight behavior are being made clear to us. For example, we found that flight activity is influenced by host plant quality and age of the whitefly. We hope to eventually be able to predict when whiteflies are going to migrate between crops. This will allow growers to make informed decisions concerning planting dates. We are also working in the field to confirm laboratory results.

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A commercial product called Beescent® containing a mixture of chemicals including chemicals used by honey bees as pheromones, was applied to watermelons in early bloom on Aug. 15, 1991. Honey bee visitation to treated, 18-row plots, were significantly higher than to untreated for only 2 days, the day of treatment and the next day. Watermelon yields were not effected. The daily high temperatures reached 86-88 °F, so that most of the chemical had volatilized away by the end of the first day.

Water Stress caused reduction of seed yield in cowpea plants by decreasing total biomass and photosynthesis. The source leaf, pod and seed water potential of stressed cowpea were lower than water potential in non-stressed plants. No differences in water potential and turgor were observed between pod walls and seed of cowpea plants. Partitioning of the total above ground dry matter was similar for both stressed and nonstressed cowpea plants. Photosynthetic rates of single leaves from cowpea were greater for nonstressed than stressed plants. The duration of seed growth of cowpea was not different between stressed and nonstressed plants; however, rate of seed growth at the end of seed filling period was greater in nonstressed plants. Seed growth rate of both stressed and nonstressed cowpea plants declined at about the same time photosynthesis of the source leaf declined. Leaf area index was greatest in nonstressed cowpea.

Three rates of the plant growth regulator Foliar Triggrr were applied to green beans grown for processing at 5% bloom. The 6 oz rate increased yields of size 1 and 2 beans compared to all other treatments and the untreated check and had the fewest size 3 beans (which would be culls). The 11 oz rate was similar to the untreated check while the 16 oz rate decreased yields. Total bean numbers per plant were similar. Although treatment differences in this experiment were not statistically significant, a yield increase of 10.2% for the 6 oz rate compared with the untreated check may well result in increased economic returns.

Most lettuce (Lactuca sativa L) seed fails to germinate at high temperatures. This phenomenon thermodormancy, is common in desert regions where 87% of all lettuce is grown in the U.S.A. A study was conducted using a non-thermodormant plant introduction, PI 251245, and two highly thermodormant Dutch butterhead cultivars, 'Dabora' and 'Severa'. Reciprocal crosses were made and germination trials conducted to observe how maternal and paternal influence and seed color contribute to thermodormancy. At 25 °C, germination was 100% for the three parents and the reciprocal F1 hybrids. Germination differences occurred at both 30° and 35 °C among the parents, with P1251245 with 100% germination and Dabora and Severa with less than 10% germination at both temperatures. Segregating F3 and F4 populations from Dabora x PI 251245 were investigated further. Genetic variation found between families suggests that breeding lettuce for improved thermotolerance may be possible. Seed color did not influence thermodormancy.

Six mulches were compared to no mulch on cantaloupes at Yuma in the Spring of 1996. The IRT film and black mulches caused "Mission" cantaloupes to produce significantly higher early yields than white mulch or no mulch. Silver mulch gave good early and total yields. All mulches seemed to favor total production but in this test differences for total yields between mulched and non-mulched plots were not significant.

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