October 30, 2002
Vol. 1; Issue 3

Production Update:

Head lettuce planting continues at a steady pace. Early planted fields appear to be 2-3 weeks from harvest, with a few fields estimated to begin harvest next week. Similarly, the early broccoli and cauliflower fields should begin harvesting soon. Romaine plantings are steady with first harvests estimated at 2-3 weeks (Fig 1). Mixed and specialty lettuces and baby spinach plantings appear to be in good shape. No major production problems have been reported. Temperatures in the three major growing areas have been around normal and are steadily declining . Presently, temperatures are about optimal for lettuce and spinach germination (Table 1). Melon harvest is in full swing in a number of fields in the Yuma Valley with quality reported to be good. Some cantaloupe and watermelons fields in the Yuma Valley have tested positive for potyvirus, Monosporascus Vine Decline (Monosporascus cannonballus), and whitefly transmitted geminivirus. (http://cals.arizona.edu/PLP/ plpext/diseases/vegetables/melon/melon.html) However, these diseases have not appeared to have had a serious impact on yields thus far.

Pest Update:

Worm pressure remains fairly steady in the head lettuce, particularly for cabbage looper. Overall though, oviposition appears to be decreasing. Budworm/bollworm activity has increased in the last week. In addition, thrips populations on post–thinning stage lettuce and older have increased and scarring on leaves is quite visible in some areas. Similarly, palestripped flea beetle (picture) remains active and should be controlled in pre-harvest lettuce. Fall armyworm has been found in low numbers on broccoli, and to a lesser extent on lettuces. Insecticides used for beet armyworm have been effective on fall armyworm. Diamondback moth populations have been reported to be high in some areas on green cabbage. Populations on broccoli and cauliflower have been light. Whitefly movement is continually declining, but a fair amount of movement was seen in the Dome Valley area in mid-October (Table 2). Thrips movement appears to be variable and leafminer adult activity appears to be declining with the cooler weather. We continue to pick up winged aphid on sticky traps, but no reports of aphid colonization has been observed on plants. The aphids collected have consisted primarily of cabbage aphid, cowpea aphid and an unidentified green aphid.

Table 1. Temperature recorded from AZMET stations at three Yuma growing locations.

Table 2. Insect activity measured from yellow sticky traps at at three Yuma growing locations.

AZMET Weather Data

Disclaimers--