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.

It can be a challenge to selectively control weeds in vegetables with the limited number of herbicides that are registered on specialty crops. You have the next 5 or 6 months to control the bank of weed seeds that can be a problem after you plant fall vegetables. This involves keeping weeds in the current crop from producing seed and extends through the summer crop or fallow period. 

Much of the wheat and cotton that are in the field now will be followed by vegetables. There are more herbicides registered for use in cotton than for any other crop grown in Arizona and with proper management, weeds should not be a problem. The herbicides that are available for use in wheat and barley is more limited although there are tools for controlling almost all of the common weeds in these crops. Nonetheless, we get calls about this time every year on what can be done now to control weeds that should have been treated earlier. At this point, it is usually necessary to wait until the wheat is maturing before applying preharvest treatments to desiccate weeds that are green, contain too much moisture and reduce grain quality. There are herbicides that are registered for preharvest use after the grain is in the hard dough stage and contains less than 30% moisture. These include both systemic herbicides like glyphosate and some PGR’s and contact herbicides like Aim. ET, Gramoxone, bromoxynil and others. Not all of these are registered here and labels need to be checked.

Fallow periods before vegetables are planted offer an excellent opportunity to control weeds that cannot be selectively controlled after the crop is planted. Depending on the length of time the field will be fallow, almost every weed can be controlled. Even very difficult perennial weeds like nutsedge can be controlled at this time. The Eptam/ fallow technique is an example of an effective and affordable treatment if 40 to 60 days are available. Non chemical treatments like flooding and solarization have proven effective in controlling not only weeds but diseases as well. At the very least, weeds can be germinated and disked to reduce the seed bank prior to planting.

Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:            
CEW moth counts decreased considerably y in the past 2 weeks and about average for late summer
 
Beet armyworm:         
Trap counts stay active in some locations (Yuma Dome Valley and Wellton) particularly near alfalfa
 
Cabbage looper:         
Cabbage looper numbers remain low consistent previous years.
 
Diamondback moth:      
DBM moths were not caught in any trap since June; average for this time of the year.
 
Whitefly:                      
Adult movement decreased in past 2 weeks consistent with previous years
 
Thrips:                         
Thrips adults decreasing in most locations, and trending comparable to previous years.
 
Aphids:                       
Aphid movement is absent and consistent with what we typically see during the summer.
 
Leafminers:                  
Adult activity has highest in Wellton and Dome Valley, and slightly above average for early August