This study was conducted at the JV farms at Gila Valley. Lettuce variety ‘Guapo’ was seeded, then sprinkler-irrigated to germinate seed on September 19, 2023, on double rows 12 in. apart on beds with 42 in. between bed centers.  Rest of the irrigation was supplied by furrow irrigation or rainfall. Treatments were replicated five times in a randomized complete block design. Each replicate plot consisted of 25 ft of bed, which contained two 25 ft rows of lettuce. Plants were thinned on October 9, 2023 at the 3-4 leaf stage to a 12-inch spacing. Treatment beds were separated by single nontreated beds. Treatments were applied by incorporating in soil before seeding or with a tractor-mounted boom sprayer that delivered 50 gal/acre at 100 psi to flat-fan nozzles spaced 12 in apart.

Month	Max	Min	Avg	Rain
September	100	71	86	0.71 in
October	93	61	77	0.00 in
November	80	51	65	0.08 in
December	71	44	57	0.82 in

 
Fusarium wilt (caused by Fusarium oxysporum f. sp. lactucae ) rating was done in the field by observing the typical symptom of lettuce wilt. Confirmation was done by cutting the cross section of roots. Disease scoring/rating was done on December 6, 2023. 
 
The data in the table illustrate the degree of disease control obtained by application of the various treatments in this trial. The disease pressure was extremely high in 2023, and most treatments showed little or no control against the disease. The treatments that showed some activity were Bexfond, Cevya, Rhyme, and Serifel. Plant vigor was normal and phytotoxicity symptoms were not observed in any treatments in this trial.

Dacthal, Prefar, and GoalTender are the primary herbicides used in the low deserts on broccoli and cauliflower. Other options include Trifluralin (Treflan), Devrinol, Stinger, Poast and Select. All of these herbicides have different characteristics and should be used differently for maximum weed control and crop safety.

Dacthal (DCPA) is effective only when applied prior to weed emergence but does not prevent weed seed germination. It is absorbed at the growing points between the radicle and cotyledon leaves. This is called the coleoptile on grasses and the hypocotyl on broadleaf weeds. Weeds sometimes emerge but stop growing. To be effective, this herbicide has to be concentrated near these growing points. It sticks strongly to the soil and needs a fair amount of water to incorporate it when using sprinklers. Furrow irrigation works as well if the bed tops are thoroughly moistened. Applying Dacthal to dry soil and incorporating it with light amounts of sprinkler or furrow water does not work. It works best when the soil is moist at application. Dacthal is fairly broad spectrum but is weak on mustards, sunflower and the thistle family.

Prefar (Bensulide) also adheres very strongly to the soil but rather than working on the region between the radicle and cotyledon leaves, it works at the root tips. Both Dacthal and Prefar are not systemic and move very little in plants. They work only where the roots and shoots contact them. Prefar must be incorporated with large amounts of sprinkler water or chemigated. Furrow irrigation, even when it thoroughly moistens the bed, will not incorporate this herbicide on most soils. Prefar is best on grasses, purslane and pigweed and will control lambsquarters and goosefoot in some situations.

GoalTender (Oxyfluorfen) differs greatly from both Dacthal and Prefar. It works primarily on the foliage, even when used as a preemergence herbicide. It is used both preemergence and postemergence and has no activity on roots or shoots. GoalTender inhibits the production of an enzyme in the plant that leads to destruction of cell membranes. It is fast acting, dependent on sunlight and acts like a contact herbicide. Even when used preemergence to the weeds, it is dependent on sunlight and the weeds must emerge from the ground. They absorb the herbicide as they emerge and twice the postemergence rate is normally required. Because a barrier is created on the surface, any disturbance of the soil after application can reduce control.

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 7, Apr 3, 2024
 
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:            
CEW moth counts remain  at low levels  in all areas, well below average for this time of year. 
 
Beet armyworm:          
Trap increased areawide; about average compared to previous years.
 
Cabbage looper:           
Cabbage looper counts increased to seasonal highs; above average for this time of season.
 
Diamondback moth:       
DBM moth counts increased in most areas. About average for this time of the year.
 
Whitefly:                      
Adult movement negligible, average for late winter. 
 
Thrips:                          
Thrips adult counts increased in most areas. Below average compared with previous years.
 
Aphids:                         
Aphid movement decreased in all areas; below average for late-March.
 
Leafminers:                   
Adults remain low in most locations, average for March.