The Effect of Time of Sweetpotato Whitefly Infestation on Plant Nutrition and Development of Tomato Irregular Ripening Disorder

Abstract

Tomato irregular ripening (TIR) disorder is associated with sweetpotato whitefly (Bemisia tabaci) biotype B feeding and is characterized by incomplete ripening of longitudinal sections of fruit. Our objective was to determine the effect of time of sweetpotato whitefly infestation on plant nutrition and the development of TIR disorder. Healthy tomato plants (Solanum lycopersicum ‘Florida Lanai’) were introduced to sweetpotato whitefly infestations at different developmental stages of plant growth: 1) five to seven true leaves, 2) flower, 3) green fruit, and 4) breaking red fruit and were compared with noninfested control plants of the same age. Plants were fertilized every 7 to 14 days. Plant nutrition was monitored over time between the noninfested control and the longest infestation interval (five to seven true leaves) and between all infestation intervals at harvest. Sweetpotato whitefly (egg, nymph, and adult) and plant parameters (height, canopy diameter, number of leaves, flowers, and fruit per plant) were taken every 7 to 14 days after sweetpotato whitefly infestation. Almost all of the fruit (99%) produced by tomato plants infested with sweetpotato whitefly at stages 1 and 2 (78 and 56 days of sweetpotato whitefly exposure, respectively) developed TIR with fruit exhibiting internal and external symptoms. Plants infested at stage 3 (35 days of sweetpotato whitefly exposure) had 79% to 80% of the fruit develop TIR. Surprisingly, 58% of fruit from plants infested at stage 4 (14 days of sweetpotato whitefly exposure) also developed the disorder, indicating that tomatoes may need to be protected from sweetpotato whitefly until harvest to avoid this disorder. Seed germination was unaffected by TIR. Plants infested with sweetpotato whitefly had mean foliar levels of calcium, copper, iron, phosphorous, potassium, magnesium, manganese, and zinc that were greater than in noninfested control plants at final harvest for both studies, regardless of time of infestation.