Just because we’re experiencing cool weather, don’t become complacent when it comes to aphids. Before the frigid weather occurred in the low desert over the holidays, aphids were beginning to colonize celery plants here at the Ag Center. However, recent temperatures in the Yuma area, and particularly in Wellton and Roll, dropped below 32° F on several nights. Experience has shown that aphid populations tend to slow down significantly under these “cold” desert temperatures. That is essentially what we observed the past week; population growth had stalled out and aphid numbers were very low. However, past experience has also shown us that aphid population growth begins to increase once the weather warms up. Our local weather forecast suggests that temperatures will be in the mid-to-high 60’s with moderate nighttime lows for the next two weeks. Assuming the weather service is correct, these conditions may be ideal for aphid population growth. Green peach aphid population growth tends to increase when temperatures average around 55-57 °F. Because we’ve seen an increase in winged aphids on our yellow sticky traps over the last month, PCAs should be extra vigilant in scouting for aphid colonies. As average temperatures increase later, foxglove aphid may become more abundant (they tend to be more biologically active under warmer temperatures; that is when avg. temps > 60 °F). If the field has been treated with imidacloprid at planting, then chances are you are in pretty good shape. But, continue to monitor as imidacloprid doesn’t generally last all season, particularly in cool, cloudy weather when the plants are not transpiring at a rapid rate. Regardless of whether you find green peach or foxglove aphid the key to effective aphid management with foliar insecticide is to initiate sprays at the time apterous (wingless) aphids begin to colonize. Of course, this requires diligent scouting and sampling. On older lettuce, make sure you thoroughly examine developing heads/hearts. Fortunately, PCAs have alternatives for foliar aphid control. For more information on insecticide alternatives please visit Aphid Management in Desert Produce Crops – 2016. So, keep your eyes open for new aphid colonies and plan according. As Sun Tzu, the ancient Chinese military strategist once said, “Rely not on the likelihood of the enemy’s not coming, but on our own readiness to receive him”

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.

The autonomous agricultural robot industry is an incredibly fast-moving space. Startups, established companies and academic researchers are continuously putting forth new ideas and products. It’s hard to keep up with. In November of 2020, Future Farming (Misset Publisher, BV, Doetinchem, Netherlands) published a Field Robots Catalogue that provides a comprehensive overview of the state of autonomous ag robots. The article provides brief summaries of 35 autonomous ag robots that are currently commercially available. Along with a brief paragraph about what each robot does, the article presents information about how many robots from a particular manufacturer are actively being used, the cost of the machine, and links to a video of the device in action. Most of the robots are for weed management in vegetable crops. Kill mechanisms range from spot spraying to mechanical weed removal to electrocution.  Several of the robots featured are applicable and relevant to Arizona vegetable production, and some are currently operating in the U.S. If you’re interested in ag robots and want to get up to date, this article is an excellent resource and quick read. The article can be found at the link provided below.

Title: Future Farming Field Robots Catalogue
https://misset.com/field-robots/field-robots/
Publisher: Misset Publisher, BV, Doetinchem, Netherlands.

Contact herbicides are those that only affect the part of the weed that they “contact” They don’t move into or affect any other part of a plant. They were the first herbicides used and surprisingly, they still are better at controlling some weeds than any other products that have been developed. They usually control only small weeds with good coverage although some of them will kill large malva , Purslane and some other difficult to kill weeds. Goal, Sharpen, Treevix and Gramoxone, which are all contacts, will kill malva and purslane while systemic herbicides like Glyphosate and 2,4-D, misses them. Maestro or Bucril (Bromoxynil), also an old contact, will kill swinecress while many systemics like the growth regulators ,miss it. Glufosinate( Liberty, Rely) is a contact that is very broad spectrum and kills more grasses and broadleaves than many systemic herbicides. These all work very fast and in this age of immediate gratification ,you don’t have to wait long.  Most have little soil residual activity (except Goal, Chateau and a couple others) Goal and Chateau are contacts but used mostly preemergence to the weeds. They “ contact” the weeds when they emerge at the surface. which is a benefit where double or triple cropping is common. Most( again except Goal) are not volatile but will cause pretty clear contact injury when the spray moves to sensitive crops. Paraquat was registered in 1959 and is still a very useful tool for desiccating plants. Many restrictions have been put on its use because of its toxicity to humans.  Most contact herbicides are non-selective and will injure most living plant tissue. They are used selectively with directed spray or timing. Adjuvants are often required to increase absorption, spreading and sticking.

Area wide Insect Trapping Network   VegIPM Update, Vol. 13, No. 13, Jun 29, 2022
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:            
CEW moth counts decreased in the past 2 weeks, but still higher than the previous 2 summers.
 
Beet armyworm:        
Trap counts remain active in some locations (Yuma Dome Valley and Tacna) but lower than last summer
 
Cabbage looper:         
Cabbage looper numbers remain low consistent with the lack of activity this fall compared to last season.
 
Diamondback moth:      
DBM counts very low and average for this time of the year.
 
Whitefly:                      
Adult movement continuing to increase, particularly in Gila and Yuma Valleys consistent with melon harvests.
 
Thrips:                           
Thrips adult decreasing in most locations, and trending comparable to this previous years.
 
Aphids:                        
Aphid movement is absent consistent with what we typically observe in the summer. 
 
Leafminers:                   
Adult activity has highest in Yuma Valley, and above average for late-June.