October 15, 2002
Vol. 1; Issue 2

Production Update: Planting of lettuce and cole crops continues at a constant pace, with mixed and specialty lettuce and baby spinach plantings starting to increase in acreage. Temperatures are gradually declining, and the cooler evening temperatures (Table 1) are ideal for stand establishment. No serious production problems have been reported in the produce crops. However, a number of melon crops have tested positive for both potyvirus and whitefly-transmitted geminivirus in the Yuma Valley, as well as in the Imperial Valley. A few fields have shown symptoms of vine decline and may be suffering from Monosporascus cannonbolis or other related soil diseases. Samples have been submitted for positive identification.

Pest Update: Worm pressure continues to be heavy in some areas of the Yuma and Gila Valleys. Cabbage looper populations remain high, and beet armyworm pressure appears to be declining slightly. Flea beetles are still active and thrips can easily be found in head lettuce. No reports of significant diamondback moth on cole crops. Whitefly movement appear to be declining with the exception of the Gila Valley where trap catches peaked last week.(Table 2). Thrips movement remains low, but leafminer adult activity appears to have increased in the past few weeks. We are beginning to pick up winged aphid on sticky traps and lettuce plants in the Yuma Valley, but no colonization has been observed on plants. The aphids collected have consisted primarily of cabbage aphid, cowpea aphid and an unidentified green aphid.

Product Updates: Intrepid 2F (methoxyfenozide; Dow AgroSciences - label) insecticide was granted a label in Arizona last week and is now available for local use in leafy vegetables and cole crops. The product is an IGR (molt accelerating compound) with good residual activity at on cabbage looper and beet armyworm at appropriate rates. A "New" EPA Label for Avaunt WG (indoxacarb; DuPont - label) insecticide with a higher use rate range of 3.5 to 6.0 oz/ac (0.065 to 0.11 lbai/ac) for lettuce (head and leaf varieties) has been approved. The compound is effective against beet armyworm and cabbage looper as well. Both products are considered reduced-risk insecticides and have excellent fits in our Lettuce and Cole Crop IPM programs. Figure 1 below provides data illustrating the relative efficacy of these new compounds against Success and Proclaim. The trial was conducted at the Yuma Ag Center in small, replicated plots (4 beds * 45 ft). Tthe data represents the residual efficacy (5, 8 and 12 days after treatment) for several rates of each compound following a broadcast application made on thinning stage lettuce (4 leaves) on September 25. In general, all insecticide treatments provided the same level of beet armyworm and cabbage looper control at 5 and 8 DAT. By 12 DAT, residual activity of all the compounds had declined.

For more information on these compounds and how they fit within our Vegetable Pest Management Programs please visit the following ACIS web pages:

• Reduced-Risk Insecticides For Leafy Vegetables and Melons http://cals.arizona.edu/crops/vegetables/insects/general/fn0502reducedrisk.html
  
• Review of New Insecticides Under Field Development For Desert Vegetable and Melon Production http://cals.arizona.edu/crops/vegetables/insects/general/reviewinsect.html
  
• Alternative IPM Programs for Management of Lepidopterous Larvae in Fall Lettuce http://cals.arizona.edu/pubs/crops/az1177/az1177-1a.pdf
  
• A Practical Approach for Managing Lepidopterous Larvae with New Insecticide Chemistries in Lettuce http://cals.arizona.edu/pubs/crops/az1143/az1143_22.pdf

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