January 12, 2004
Vol. 2; Issue 4

Production Update:

Planting of many vegetable crops has almost ceased, with the exception of mixed and baby leaf lettuces and spinach. Harvest activity remains steady for all produce crops, particularly in the Yuma Valley where temperatures are the most moderate this time of the season (Table 1). Soil temperatures remain low but appear to be increasing with the warmer temperatures we are currently experiencing. We have had no measurable rainfall since mid-November. Markets appear to be steady and produce quality is excellent. No reports of major mildew or disease problems. Planting of cantaloupe and honeydew crops has been observed in the Yuma Valley under plastic (mid-bed trench).

Pest Update:

Area-wide Trapping Network: Based on our trap catches in the Yuma Valley, insect activity remains to be at seasonal lows for whiteflies, leafminers and thrips (Fig 1). Similarly, aphid flight activity is on the decrease consistent with observations from last year (Fig 2). A large proportion of the alates captured has been cabbage aphid, green peach aphid, and cowpea aphid which are presently colonizing in alfalfa (http://ag.arizona.edu/crops/counties/yuma/ farmnotes/fn0101cowpea.html) .

Worms: Worm activity is light, but new hatches of beet armyworm and cabbage looper larvae have been observed on head lettuce at the Yuma Ag Center. Increased larvae activity should be expected with warmer temperatures.

Thrips: Thrips numbers on head and romaine lettuce appear to be increasing. PCA’s should begin to closely monitor for presence of larvae and damage. For more information on sampling and management visit the following publications:
http://agriculture.state.az.us/CD&P/ADS%20Specialty%20Crop%20%20Grant_%20Palumbo%20AILRC.pdf (9/03 AZ Dept. of Ag. Specialty Crop Grant Report), PDF file, 667KB

http://agriculture.state.az.us/CD&P/AILRC%20Reprot%200203%20Palumbo.pdf (9/03 AZ Lettuce Research Council report), PDF file, 1.67MB

Aphids: Green peach aphids remain abundant on untreated head lettuce at the Yuma Ag Center. In some plots we have measured > 5 aphids per plant. Although these numbers are not damaging, if not managed they may result in significant infestation at harvest. We have also found Foxglove aphids colonizing untreated head lettuce for the first time this year at the Yuma Ag Center on untreated head lettuce. This occurrence is similar to what we observed last year as well. PCA’s should begin to intensify their aphid monitoring if they have not already started to do so. This would include sampling a higher number of plants, particularly near housing developments, citrus orchards and the Colorado River. For further information visit:

http://ag.arizona.edu/crops/vegetables/insects/advisories/2002/vegadv111502.html#pest

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

Fig 1. Sticky Trap Catches for the Yuma Valley, 2003-2004

AZMET Weather Data
Search for Pest Photos

Disclaimers--