Hope you are all enjoying the summer so far and keeping busy. Although, we’re about 2 months away from the Fall produce season, it’s never too early to begin thinking of IPM strategies you will be using to battle key insects next season. This includes keeping track of their typical activity during June, July, and August. Below is a short discussion detailing individual pests. 
 
Aphids:    The major aphid species that are important in produce crops each spring include green peach aphid, foxglove aphid and lettuce aphid.  These species are considered cool season pests and are biologically most active during the winter and spring when temperature average around (55-65 F). We do not find them on summer crops as the high temperatures prohibit their activity. They essentially become extinct each summer only to reappear in the fall to infest crops in Oct-Dec migrating into the desert via N-NW winds that occur after the monsoons.
 
Diamondback Moth (DBM):  Another key pest that disappears each summer but for a different reason than for aphids. The host range of DBM is limited to only brassica crop and plants. Although brassica weeds are common during the winter, they occur during the summer due to high temperatures and dry conditions. Thus, like aphids, DBM populations from the previous spring season become “extinct” during the summer when brassica crops and weeds are absent. They reappear each fall migrating in on high winds associated with tropical storms from Mexico, or arrive into the region on infested brassica transplants from California.
 
Whiteflies:       A resident pest that occurs year-round in the desert. As a warm season pest, whiteflies are most abundant on fall produce crops, and seldom a problem during the winter and spring. Peak abundance occurs during the summer months on cotton, and again in September and October on fall brassica, leafy vegetables and fall melons.  Thus, it is important to control whiteflies in cotton prior to defoliation to prevent large migrations onto fall produce crops. In addition, whiteflies can be found on several weeds such as purslane, goosefoot, ground cherry, and sunflowers. Sanitation in and around fields being prepped for fall plantings is important. Preventatively, growers should consider applying soil, system insecticides such as imidacloprid or Verimark to Fall produce crops.

Beet Armyworm (BAW):  A warm-season pest that occurs year-round in the desert. They tend to reach peak abundance twice a year. Generally, the most important peak is in September and October when weather is ideal for their development, flight activity and oviposition. A second peak occurs in late spring. Activity is generally light during the summer, occurring primarily in alfalfa crops. Although BAW is known to migrate in from the south via monsoon and tropical storms, resident populations annually occur in alfalfa during the summer. Thus, to minimize BAW in fall produce crops, thorough management of BAW can potentially minimize their movement onto Fall produce crops.  Weeds are also a source of BAW (purslane, goosefoot, sunflower and Russian thistle) so sanitation in and around fields is important.
 
Western Flower Thrips (WFT):  Also a resident pest that can be found in the desert year round. WFT is most abundant on lettuce in the late spring, but peaks in abundance on alfalfa, melons and cotton is May and June. During the late summer numbers drop dramatically where thrips can be found on melons and alfalfa and weeds like goosefoot and purslane. WFT slowly move into lettuce again in early fall and are least abundant during the winter.  Sanitation of weeds during the summer can help reduce thrips abundance moving into the fall crops and weeds.
 
For more information see:   Keeping Track of Major Produce Pests During the Summer

As part of the Southwest Ag Summit (SWAS) that took place in Yuma in late February, we conducted a breakout session on Thursday, 22 February 2024 titled “Colorado River Water Shortage: Agricultural Perspectives”.  
This session provided a brief review of the background, the current situation on the Colorado River, and very importantly it included an outlook on the current discussions among the basin states to negotiate a new compromise for the guidelines of use under conditions of water shortage.  These new guidelines will go into place at the end of 2026.  Both the upper and lower basin states have now submitted draft proposals to the Bureau of Reclamation (BoR) on 6 March 2024.
This breakout session at the Southwest Ag Summit provided up to date information and first-hand insight into the process.  The participants were each uniquely qualified to offer valuable perspectives on these issues.  
The participants included Elston Grubaugh, Wellton-Mohawk Irrigation and Drainage District, who introduced the discussion and served as program moderator.  Bart Fisher, Palo Verder Irrigation District and State of California Colorado River Water Board member, Fisher Ranch, Blythe CA, provided a California perspective with a background of extensive experience in Colorado River management over several decades.  Hank Auza, Yuma County Water User’s Association President and Yuma Ag Water Coalition representative, Barkley Co. of Arizona, Yuma AZ, provided an Arizona perspective.  
Elston has extensive experience working in irrigation districts on both the California and Arizona sides of the Colorado River.  He has a valuable perspective, and he plays an important role in the management of Colorado River water in the Yuma area.  We are fortunate to have Elston provide his direction for this program and offer his point of view.
Both Bart and Hank are directly involved in the ongoing reconsultation negotiations directed at developing the new Colorado River management guidelines that will go into place in 2026.  Both are part of their state's delegation in the current negotiations and represent the lower basin.  Bart and Hank are not only responsible for representing California and Arizona, but they are both active farmers in the Palo Verde Valley and Yuma area valleys, and they bring valuable perspectives to the discussions.
The goal of negotiations among the seven U.S. Colorado River basin states has been to submit a single document proposing guidelines to the BoR.  However, as was discussed at this program at the SWAS, the upper and lower basin state groups have been dealing with significant differences and were not able to come to a consensus agreement.  As a result, the upper and lower basin delegations each submitted separate proposals to the BoR in early March.
There is still a chance that both the upper and lower basin state groups can reach a common agreement for a unified proposal.  In the meantime, both proposals are under review by the BoR. Officials with the BoR have indicated that they will be working with the basin states in the next six months to develop a consensus draft proposal for post-2026 river management by the end of 2024.
Further details on the two proposals submitted on 6 March 2024 by the upper and lower basin groups and contrasting the two will be forthcoming in a future article.
For the excellent program that was provided at the 2024 SWAS, I want to thank Elston, Bart, and Hank for their outstanding presentations.  Each of the participants in this program brought a wealth of knowledge and experience to the discussion.  
Specifically for Bart and Hank, we are all indebted to them for their contributions and hard work while serving on the lower basin state delegations during these critical and challenging negotiations.  Their firsthand perspectives and contributions to this program are very much appreciated.

Past few weeks have been stressful for everyone but plants do what they want to do. The timing could have been better though. In the last few weeks we have seen our own version of pandemics in plant world in Yuma area.

Botrytis rot:
The first problem that hit us hard is botrytis rot. Usually not a big problem in desert southwest, this year has been different. With ‘excessive’ amount of rainfall we got this year, botrytis literally had a field day in many fields. Field diagnosis is fairly easy, you will see the gray fuzzy growth, and sometimes you can see ‘melanized’ sclerotia. Not to be confused with sclerotia of Sclerotinia sclerotiorum (see pic). The disease has been more severe in head lettuce than romaine. If one variety has has succumbed to death compared to other varieties in the same field/condition it might be a smart choice to plant another variety next year. Use drop or furrow irrigation instead of sprinklers. If sprinklers have to be used, irrigate morning or early afternoon giving enough time for foliage to dry.

Sclerotinia drop:
We have had few fields infected with sclerotinia, thankfully we did not have devastating airborne infection like we had last year. The disease is caused by fungi Sclerotinia sclerotiorum and Sclerotinia minor. Both species survive on soil as sclerotia for several years. Cool and wet weather favor the germination of sclerotia in soil. Upon favorable conditions sclerotia manages to have eruptive germination releasing millions of spores in air thus becoming airborne. It is difficult to predict when the disease becomes airborne as the fungi have specific requirements to be airborne.

Management practices include use of subsurface drip irrigation, keeping the top 5-8cm of soil on planting bed is crucial. Deep plowing, crop rotation with non-hosts like small grains and broccoli, removal of infected plant tissue from the field etc. help reduce the inoculum level. Soil fumigation is effective though may not be economical. If you have a field with high infestation of these two fungi, flooding the field for 4-6 weeks in summer has been reported to result in almost 100% control.

Fusarium wilt:
We have been seeing some fields with fusarium wilt. It is not as severe as in fall but is something to keep in mind for fall planting. If you think that particular portion of the field is a hotspot for fusarium, flag the area and keep an eye for symptoms development in fall. Flagged area can also be used to plan the cultural operation in the field. When introducing manpower/equipment’s in the field treating the flagged area at the very last will reduce dispersal of inoculum to healthy part of the field.

“Plant clinic is closed because of COVID19 but if you need diagnosis please text 928-920-1110 with the field map and we will do the field diagnosis”

Finally, a big thank you to everyone in agriculture for holding the fort, making sure people have food in their table. Not all heroes wear a cape, some just do a thing called farming!

Our newly constructed self-propelled steam applicator is designed to inject steam into the soil and raise soil temperatures to levels sufficient to kill weed seed and soilborne pathogens (140°F for > 20 minutes). After the soil cools (< ½ day), the crop is planted into the disinfested soil. We have done some preliminary testing and are very encouraged. Results show that the machine is able to reach target temperatures at reasonable travel speeds, provide uniform temperature distribution across the bed and form nicely shaped beds suitable for subsequent planting. We still have some bugs to work out and identified improvements to make before shipping the unit to Salinas, CA where we will conduct field trials with crops this summer. If you are interested in seeing the machine operate or more information about soil steaming for soilborne pest control, please feel free to contact me.
Check out a video of the machine operating by clicking here or on the image below.

Fig. 1. Initial testing of self-propelled steam applicator video.

Acknowledgements
This project is sponsored and funded in part by the Propane Education and Research Council (PERC), Arizona Specialty Crop Block Grant Program and USDA-NIFA. We greatly appreciate their support.

We did some trials at the University of Arizona Yuma Agricultural Center in broccoli to evaluate and compare Napropamide (Devrinol) liquid formulation 2XT versus the Dry formulation DF-XT. 
This product inhibits the production of fatty acids in plants, which is crucial for plant development. It affects primarily the meristematic cells which are in growing points of the stems and roots. We saw activity especially on seedling development that we show in some pictures at the end of the article. 
Some growers expressed their concern on the safety of different levels of incorporation with sprinkler irrigation. Therefore, we established a test in which we applied the product as a broadcast application after planting. Then we used different levels of incorporation in some sections using 12, 24 and 36 hours of sprinkler irrigation. No difference was observed with the incorporation level in our trial. We observed temporary phytotoxicity from 4-10%. The data was obtained from visual evaluations. Also, a 0.5 to 1” height reduction was exhibited when compared to untreated plots. 
It is common that growers and PCAs make management decisions on herbicide applications in different crops knowing that some injury is expected. Such is the case for alfalfa, wheat, spinach, lettuce and in this case broccoli. Frequently slight stunting it is not noticed because commercial fields don’t have untreated areas for comparison.
We talked to PCA’s and growers at the SW Ag Summit and asked for their experience with napropamide this past season. Some noticed the broccoli exhibited similar levels of phyto, which they considered economically tolerable. 
We noticed that good soil prep was important for before the application of the product and avoiding direct contact of the seed with the product for best results.
On weed control we noticed good activity on nettleleaf goosefoot and lambsquarter. 
At the 45day we collected data counting SMALL and LARGE weeds and at the 60 day evaluation we noticed most of the SMALL goosefoot and lambsquarter in the high rate of napropamide plots stayed small (pic. below).

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 21, Oct 16, 2024

Results of pheromone and sticky trap catches can be viewed here.

Corn earworm: CEW moth counts increased in most traps; about average for early October.

Beet armyworm: Trap counts increased in most areas last week, and about average for early October.

Cabbage looper: Cabbage looper trap counts still most locations, below average for this time of the season.

Diamondback moth: Adult activity increasing, particularly in the Yuma and Dome Valleys.  Above average for this time of season.

Whitefly: Adult movement increasing Tacna, Dome Valley and Yuma Valley; overall about average for early October.

Thrips: Thrips adult movement picking up in all areas, overall activity above average.

Aphids: Winged aphids beginning to show up the north Yuma and Gila Valleys; about average for early October.

Leaf miners: Adult activity light in all areas, about average for this time of season