Population of the Sweetpotato Whitefly in Response to Different Rates of Three Sulfur-Containing Fertilizers on Ten Vegetable Crops

Whiteflies in the Bemisia complex are global pests on numerous horticultural crops. The effect of cultural practices on the population of the B-biotype sweetpotato whitefly, Bemisia tabaci (Gennadius), is only partly understood. A study was conducted to examine the effect of different rates of three common sulfur-containing fertilizers (ammonium sulfate, potassium sulfate, and superphosphate) on the population of B. tabaci in 10 vegetable crops. Three different rates were tested in the field for each fertilizer, but the specific rates were varied among crops to reflect the general use by growers in comparison with higher and lower rates. Egg, nymph, and adult whitefly counts were generally elevated with increased rates of ammonium sulfate or decreased with increasing rates of potassium sulfate. Conversely, field and laboratory data suggested a reduction in whitefly counts on cabbage and cucumber in response to increased rates of ammonium sulfate. However, whitefly populations within crops were generally the same regardless of rate of the superphosphate. Although each of the three fertilizers provides more than one essential nutrient, the individual role of sulfur, or any other nutrient, on the whitefly population was not identified. Nevertheless, the results from this study support that in certain sulfur-containing fertilizers, populations of the sweetpotato whitefly can be affected in several vegetable crops.