With the spring melon deal in Yuma finishing up in the next couple of weeks, now is the time to begin thinking about whitefly management in fall produce and melons crops. The first line of defense in avoiding whitefly issues in the fall produce/melon plantings is for PCAs and growers to do a good job of controlling whiteflies on cotton this summer. But before whitefly management begins in cotton, it is important that whitefly populations be prevented from building up to large numbers in the spring melons that have recently finished, or are nearing completion of harvest in the next few weeks. Although whitefly numbers have been relatively lighter this spring than normal, adult numbers have increased significantly over the past week in melons coinciding with higher temperatures and area-wide melon harvests. Growers and PCAs should not hesitate to knock these populations down on pre-harvest melons. Under current weather conditions (high temperatures) immature populations can rapidly build-up and cause honeydew/sooty mold contamination on fruit. Once harvest is complete, proper sanitation in spring melons is critical for preventing unnecessary whitefly migration into cotton and alfalfa. It is highly recommended that melon growers quickly destroy plant residue as soon as possible following harvest. A delay in disking under melon fields following harvest can provide a large source of adult whiteflies that will readily disperse into cotton and alfalfa, especially if they don't need to fly very far. These fields also potentially extend the host-acquisition period for CYSDV. Once melons fields have been disked and flat-watered, it is common for volunteer melons to germinate and emerge during July. The destruction of volunteer melons between spring and fall crops can reduce the source of whiteflies and virus inoculum available. This can be done by disking or applying a contact, burn-down herbicide to fields. Volunteer plants should be destroyed as soon as practical. Recent research has indicated that fall melons grown near spring melons with volunteers (<1.8 miles) are at a high risk of CYSDV infection. Ideally, it is in the Ag community’s best interest to use sound cultural management practices, such as sanitation, to eliminate and avoid unnecessary sources of whiteflies before the fall produce and melon seasons begin. For more information on cultural management practices for whiteflies see: Insect Management on Desert Melons: Whiteflies.

Name this Insect Pest. - Lettuce Aphid

This study was conducted at the Yuma Valley Agricultural Center. The soil was a silty clay loam (7-56-37 sand-silt-clay, pH 7.2, O.M. 0.7%). Spinach ‘Revere’ was seeded, then sprinkler-irrigated to germinate seed Jan 18, 2024 on beds with 84 in. between bed centers and containing 30 lines of seed per bed.  All irrigation water was supplied by sprinkler irrigation.  Treatments were replicated four times in a randomized complete block design.  Replicate plots consisted of 15 ft lengths of bed separated by 3 ft lengths of nontreated bed.  Treatments were applied with a CO₂backpack sprayer that delivered 50 gal/acre at 40 psi to flat-fan nozzles. 
 

Month	Max	Min	Average	Rainfall
January	68	42	54	1.14 in
February	73	47	59	0.50 in
March	77	50	63	0.31 in

 
Downy mildew (caused by Peronospora farinosa f. sp. spinaciae) was first observed in plots on Feb 19  and final reading was taken on February 26, 2024. Spray date for each treatments are listed in excel file with the results.   Disease severity was recorded by determining the percentage of infected leaves present within three 1-ft² areas within each of the four replicate plots per treatment.  The number of spinach leaves in a 1-ft² area of bed was approximately 144. 

The data (found in the accompanying Excel file) illustrate the degree of disease reduction obtained by applications of the various tested fungicides. Products that  provided effective control against the disease include Orondis ultra, Thrive 4 M, Fungout, Cevya, Eject and Zampro. No phytotoxicity was observed in any of the treatments in this trial.

This is the time of year when people start to regret not controlling weeds earlier in wheat. Uncontrolled weeds begin to become more visible and both the crop and weeds are too big for most herbicides. The weeds not only produce millions of little time bombs (seeds) but can contaminate the crop and make harvest difficult. There are some herbicide options at this point but none are great and all of them can only be applied when the wheat is in the hard dough stage and the crop is essentially done.
If the wheat isn’t too far along, both Simplicity and Osprey will control some big broadleaf and grass weeds. They may not be killed but they likely will stop growing. These herbicides can only be applied up to the jointing stage and most vegetables cannot be planted for 5 to 9 months following simplicity or 10 months following Osprey. The growth regulators( 2,4-D,dicamba,MCPA and others) can only be applied up to tillering or the heads will be distorted and yield reduced.    All of the preharvest herbicide options can only be applied when the wheat is in the hard dough stage and the crop is essentially finished. Therefore, if the wheat is too far along now, you likely will have to wait. A few of the options include:
Glyphosate:
Do not use on wheat grown for seed. There is a zero tolerance for this herbicide in wheat for export to some countries and it also has the potential to reduce seed germ. This may be an option, however, for grain intended for other uses that is seriously contaminated with weeds. Applying glyphosate too early will damage the crop. There is a preharvest interval of 7  days and this treatment is likely to be slow. Application will have to be by air and drift should be avoided as glyphosate is none selective.
Aim/Shark
This is a contact herbicide and will work as a desiccant without systemic activity. There is a preharvest interval of 3 days and results can be slow. Systemic activity is not necessary since this will be used as a burndown harvest aid treatment. Paraquat is not registered for wheat.
Growth Regulators(2,4-D,Clarity,Dicamba)
These are highly systemic and volatile. They will need to applied by air and will be difficult to use after march.  These may be an option in isolated areas. There is a 7 to 14 day preharvest interval and the plantback interval can be from 1 to 6 months to many vegetable crops.

Area wide Insect Trapping Network   VegIPM Update, Vol. 12, No. 15, Jul 28,  2021
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:            
CEW moth counts decreased significantly since mid-June comparable to what we observed last summer.
 
Beet armyworm:         
Trap counts remain low in most locations  and are trending similar to last summer.
 
Cabbage looper:         
Cabbage looper numbers remain low consistent with the lack of activity this fall and summer compared to last season.
 
Whitefly:                     
Adult movement continuing to increase rapidly, particularly in Wellton and Dome Valley consistent with the termination of spring melons.
 
Thrips:                          
Thrips adult movement continuing to decline to numbers comparable to this time last year.
 
Aphids:                        
Aphid movement has been absent for the past 2 months typical with high summer temperatures.  
 
Leafminers:                 
Adult activity slightly above for mid-summer.
 
Diamondback moth:    
DBM trap counts have been zeroed out in all trap locations for all of July consistent with trends observed over the past 5 years.