Kai Umeda
Maricopa County Cooperative Extension
University of Arizona, Phoenix, AZ

Introduction

All melons were treated for insect pests in 2002 (Table 3). All melons were treated at planting time for insects and 100% of the fall cantaloupes and honeydews were treated with a foliar insecticide, primarily for whiteflies. Ground dwelling insects, whiteflies, and cabbage loopers were treated in all of the melons. Ground dwelling insects in one situation required up to five applications of insecticides. Spring cantaloupes were sprayed once in Yuma by one respondent and no application of insecticide in Maricopa County by another respondent. Three to four applications were required for whiteflies in the fall cantaloupes. Spider mites occurred in watermelons and required treatment on some acreages. Beet armyworm also occurred but did not warrant any treatment. Leafminers were found on fall cantaloupes and honeydews and required up to two treatments. Aphids were not observed in 2002.

Powdery mildew occurred in all melons and accounted for most of the fungicide applications (Table 4). Vine-decline disease affected on 4% of the spring cantaloupe crop and up to 77% of the watermelon crop. Vine-decline disease was not observed in any of the surveyed cantaloupes or honeydews. In fall cantaloupes, an unidentified soil-borne disease was observed as were other unspecified foliar diseases on honeydews and cantaloupes. Viruses were not observed in 2002.

Over 80% of the cantaloupe and honeydew crops were treated with a herbicide compared with fewer watermelon fields being treated (Table 5). Most of the melon acreages were treated at planting time with few acres treated with postemergence herbicides for grass weeds. Pigweeds and purslane were problems on 24% of the spring cantaloupe fields with perennial grass weeds and nutsedge infesting 14% of the fall cantaloupe. A higher percentage of watermelon fields were observed to be infested with more weeds.

Three respondents provided estimates of melon crop yield reductions (Table 2). One respondent reported observed losses in spring cantaloupes and watermelons, one reported only spring melons, and one reported only fall melons. Weather conditions were cited consistently for causing melon yield reductions. Market conditions were cited for the highest yield reductions in spring cantaloupes and watermelons. Weeds, insects, and diseases contributed to slight yield losses. Powdery mildew, vine-decline disease, nutsedge, cabbage loopers, and spider mites were reasons for crop losses.