Historically, our Areawide Pheromone and Sticky Trap monitoring for insects was terminated around the first of April as the produce season ended. Beginning 4 years ago however, we continued our Areawide Trapping Network throughout the summer to collect trapping data from all 15 areawide trap locations year-round.  So why is this additional trapping data useful? For several reasons: 

1) Understanding the activity of some of our key pests when produce is not grown during the summer may give us an indication of what to expect as the fall produce season begins. This may be particularly helpful for predicting moth flights and whitefly flights in August-September coinciding with early transplanting and direct seeded crops.  Another example is keeping track of corn earworm which can unexpectedly show up near the beginning of fall harvests. 
 
2) Trapping for pests during the summer has shown us that 2 of our more important produce pests are not caught in traps during the summer. We presume this is due to the absence of brassica crops and weeds for diamondback moth, and high daytime/nighttime temperatures lethal to aphids. The fact that trap catches resume in the fall supports our conclusion that these pests are absent in the summer, only to reenter the desert via winds and/or transplants in the fall. And finally, 

3) It gives me something to do in the summer other than write reports and papers. 
So, visit the Areawide Summer Trap Network if you’re curious what our key pests are up to.

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.

Nutsedge has long been one of our most difficult to control weeds. It is often misunderstood and progress in controlling it has been slow. Nutsedge is often referred to as nutgrass although it is neither a grass nor a nut and is very different from both. It is a monocot, like grasses, but is in the sedge or Cyperaceae family. The nut refers to the below ground tubers which are not nuts but do have nutritional value and are sometimes eaten in famine stricken areas of Africa. There are more than 5,000 separate species of sedges that exist worldwide. Some of the most widely known sedges are water chestnut and papyrus sedge which was used to make the ancient writing material. Sedges are easily distinguished from grasses by their solid triangular flower stems. Sedges are almost all perennials while grasses, which have round stems, are most frequently annuals. It has been called the “world’s worst weed” because it can be found in every continent and in every state. The two sedges that are a problem here are purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus). While both are here, purple probably accounts for 75 to 80%. They are not hard to identify but people sometimes have trouble distinguishing them. They are both perennials and grow actively at the same time. Both grow from tubers and rhizomes. The seed is rarely viable and they spread vegetatively from these tubers and rhizomes. They spread so rapidly and are so prolific that people are often surprised that less than 5% of the seed they produce is viable. The leaves do not have ligules or auricles and have a ridge along the midvein. Yellow and purple nutsedge are similar at early growth stages but are not hard to distinguish later on. The leaves of purple are blunt and less pointed than yellow. As expected, the seedheads of purple are purple and yellow are yellow. The tubers of purple are much larger than yellow. They are irregular shaped, connected by chains, bitter in taste and have a distinctive almond odor. Yellow nutlets are small, round, not connected and have a more sweet taste. Nutsedge is one of those weeds that gets worse each year because of the absence of highly effective herbicides and because cultivation spreads it. Remember that the seed is not viable and the only way this weed spreads significant distances is mechanically. Soil movement should be minimized as much as possible where nutsedge is a problem. This is contrary to the belief that repeatedly bringing the nutlets to the surface to desiccate will control it. Many techniques have been used to try to control it over the years ranging from hand pulling to soil fumigants. Almost all herbicides that have activity on this weed are only partially effective and require multiple applications over multiple years. It is necessary to control the below ground nutlets and rhizomes and they can persist for many years and continually put out new growth. Nutsedge is so prolific that if an herbicide is not highly effective, the infestation is back to where you started one year later. Several herbicides have nutsedge on the label and range in control from 20 - 90%. Twenty of these herbicides are contained in the table "Herbicides with Activity on Nutsedge". 

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 20, Oct 2, 2024
 
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:             
CEW moth counts low in most traps; below average for this early produce season. 
 
Beet armyworm:         
Trap counts decreasing in most areas, and below average for late September
 
Cabbage looper:          
Cabbage looper trap counts low in all locations, typical for mid-late September.
 
Diamondback moth:   
Adult activity beginning to pick up in Dome Valley.  Overall, typical of late September with minimal monsson activity.
 
Whitefly:                       
Adult movement most active in Dome Valley; overall below average for mid September
 
Thrips:                          
Thrips adult movement light; overall activity typical for September. 
 
Aphids:                        
Aphid movement absent so far; anticipate activity to pick up when winds beginning blowing from N-NW. 
 
Leafminers:                  
Adult activity light in all areas, about average for this time of season.