With early-planted head lettuce crops beginning to rosette and folding-in to form heads, it would be wise to keep a keen eye out for corn earworm (CEW).  This fall could be important as pheromone trap catches spiked 2 weeks ago in Wellton and Dome Valley, and moths continue to be active.  Plus, the weather for the next 7 days is near optimal for CEW development.   Although pheromone trap counts don’t always correlate to field infestations, we have associated peak CEW moth trap counts with larval CEW activity in surrounding lettuce fields in the past.  With the calm, warm nights expected to continue for the next 7 days, above average moth activity should be expected. Lots of moths usually means lots of eggs.

CEW can be very damaging in early fall head lettuce crops. On older plants beginning to form heads, larvae will migrate to the succulent terminal growth. If not controlled before the plant leaves fold in, they are protected from foliar sprays. By this time in plant growth, at-planting soil applications of Coragen or Verimark may not be effective enough to protect the heads. Once head formation begins, newly hatched larvae will usually bore into the head almost at once upon hatching.  Corn earworm is much more likely to bore into lettuce heads than other Lepidoptera larvae, rendering the heads unmarketable.  Larvae may enter the head from any point on the plants but can often be found burrowing in from the lower half of the head.  If fields are not watched closely, infestations may not be noticed until the head is harvested. Once inside the head, it is virtually impossible to control the larvae with insecticides. Thus, pay careful attention for newly oviposited eggs (laid singly) on lettuce plants. If you are beginning to find eggs and suspect that CEW are active in the field when plants are beginning to head or cup over, you should treat as soon as possible.  Moreover, during late October and early November it is probably a good idea to prophylactically apply a pyrethroid, methomyl or acephate in combination with another larvicides (e.g., Radiant, Coragen, Proclaim) when heads begin to form.  The UA nominal threshold for CEW in head lettuce from the beginning of heading to harvest is 1-2 larvae / 100 plants (1-2%).  Repeated insecticide treatments may be required to maintain low population levels if heavy pressure is sustained near harvest.  Lab bioassays have shown that CEW larval mortality is most rapid when exposed to Lannate at 0.5 lb (>90% mortality in 1 hr after exposure) and pyrethroids at high rates (>90% mortality in 3 hrs), followed by Radiant, 5 oz (>90% mortality in 12 hrs).  By 24 hrs, mortality was 100% for all the treatments including Coragen and Proclaim.  For more information on CEW management see Corn Earworm Management on Desert Produce. 

Southwestern Chile Production
Chile (Capsicum annuum) production is an important aspect of vegetable crop production systems in the desert Southwest.  In many respects, chiles are a trademark feature of crop production in the desert Southwest.  The Southwestern (SW) Chile Belt extends from southeast Arizona, across southern New Mexico, into far-west Texas, and northern Chihuahua, Mexico.  The SW Chile Belt is dominated by production of New Mexico-type chile, also commonly referred to as “Hatch chile” and sometimes referred to as “Anaheim” type chile.  
Recent acreages across the SW Chile Belt have consisted of approximately 7-8,000 acres in NM, 3-4,000 in TX, approximately 90,000 acres in Chihuahua, and about 300-500 acres in Arizona.  Chiles are often associated with New Mexico, but Arizona also has a strong connection to this chile industry.  For example, the Curry Chile Seed Company, based in Pearce, AZ, provides the seed for >90% of the total green chile acreage across the SW Chile Belt.
Chile peppers (Capsicum species) are among the first crops domesticated in the Western Hemisphere about 10,000 BCE (Perry et al., 2007).  The Capsicum genus became important to people and as result, five different Capsicum species that were independently domesticated in various regions of the Americas (Bosland &Votava, 2012).  Early domestication of chile peppers by indigenous peoples was commonly driven for use as medicinal plants.  Due to their flavor and heat characteristics, chile peppers are a populate food ingredient in many parts of the world, including Latin America, Africa, and Asia cuisines.  Chiles have been increasingly important to the U.S. and European food industries, particularly as these populations become more familiar with chile (Guzman and Bosland, 2017).
 
There are five domesticated species of chile peppers. 1) Capsicum annuum is probably the most common to us and it includes many common varieties such as bell peppers, wax, cayenne, jalapeños, Thai peppers, chiltepin, and all forms of New Mexico chile. 2) Capsicum frutescens includes malagueta, tabasco, piri piri, and Malawian Kambuzi. 3)Capsicum chinense includes what many consider the hottest peppers such as the naga, habanero, Datil, and Scotch bonnet. 4) Capsicum pubescens includes the South American rocoto peppers. 5) Capsicum baccatum includes the South American aji peppers.
 
The Capsicum annuum species is the most common group of chiles that we encounter and there are at least 14 very different pod types in this single species that includes: New Mexico (aka Anaheim), bell peppers, cayennes, jalapeños, paprika, serrano, pequin, pimiento, yellow wax, tomato, cherry, cascabel, ancho (mulato, pasilla), and guajillo (Guzman and Bosland, 2017).
Crop Phenology
Plants vary tremendously in their physiological behavior over the course of their life cycles.  As plants change physiologically and morphologically through their various stages of growth, water and nutritional requirements will change considerably as well.  Efficient management of a crop requires an understanding of the relationship between morphological and physiological changes that are taking place and the input requirements.  
 
Heat units (HUs) can be used as a management tool for more efficient timing of irrigation and nutrient inputs to crop and pest management strategies.  Plants will develop over a range of temperatures which is defined by the lower and upper temperature thresholds for growth (Figure 1).  Heat unit systems consider the elapsed time that local temperatures fall within the set upper and lower temperature thresholds and thereby provide an estimate of the expected rate of development for the crop.  Heat unit systems have largely replaced days after planting in crop phenology models because they take into account day-to-day fluctuations in temperature.  Phenology models describe how crop growth and development are impacted by weather and climate and provide an effective way to standardize crop growth and development among different years and across many locations (Baskerville and Emin, 1969; Brown, 1989).  
 
The use of HU-based phenology models are particularly important and applicable in irrigated crop production systems where water is a non-limiting factor.  Water stress will alter phenological plant development and it is a major source of variation in crop development models.  Accordingly, irrigated systems are more consistent in crop development patterns and HU models can be much more consistent and reliable.
 
Chiles are a warm season, perennial plant with an indeterminant growth habit that we grow and manage as an annual crop.    The fruiting cycle begins at the crown stage of growth and continues until the plant reaches a point of “cut-out” with hiatus in blooming as the plant works to mature the chile fruit crop that has been developed.  
 
The first step in developing a phenological guideline for chiles would be to look for critical stages of growth in relation to HU accumulation.  Figure 2 describes the basic phenological baseline for New Mexico – type chile and was developed from field studies conducted in New Mexico and Arizona (Silvertooth et al., 2010 and 2011; Soto et al., 2006; and Soto and Silvertooth, 2007). 
 
Water and nutrient demands coincide with the fruiting cycle and efficient management of irrigation water and plant nutrients is enhanced by tracking crop development in the field.  The use of HUs (86/55 ^oF thresholds) can be applied since the thermal environment impacts the development of all crop systems, including chiles, (Figures 2 and 3).
 
Use of HUs to predict chile development is generally superior to using days after planting due to the simple fact that the crop responds to environmental conditions and not calendar days.  This approach, using phenological timelines or baselines, works best for irrigated conditions where crop vigor and environmental growth conditions are more consistent than in non-irrigated or dryland situations where irregularity in year-to-year rainfall patterns can alter growth and development patterns significantly.  Accordingly, water stress in an irrigation system will alter phenological plant development and usually accelerate crop maturity and create an earlier crop and increase fruit abortion or cause smaller fruit development.
 
Crop Phenology Relationship to Nutrient and Water Demand
Phenological guidelines can be used to identify or predict important stages of crop development that impact physiological requirements.  For example, a phenological guideline can help identify stages of growth in relation to crop water use (consumptive use) and nutrient uptake patterns.  This information allows growers to improve the timing of water and nutrient inputs to improve production efficiency.  For some crops or production situations HU based phenological guidelines can be used to project critical dates such as harvest or crop termination.  Many other applications related to crop management (e.g., pest management) can be derived from a better understanding of crop growth and development patterns.

Figure 1.  Typical relationship between the rate of plant growth and development and temperature.  Growth and development ceases when temperatures decline below the lower temperature threshold (A) or increase above the upper temperature threshold (C).  Growth and development increases rapidly when temperatures fall between the lower and upper temperature thresholds (B).




Figure 2.  Basic phenological guideline for irrigated New Mexico-type chiles.

References

Baskerville, G.L. and P. Emin.  1969.  Rapid estimation of heat accumulation from maximum and minimum temperatures. Ecology 50:514-517.

Bosland, P.W., E.J. Votava, and E.M. Votava. 2012. Peppers: Vegetable and spice capsicums. Wallingford, U.K.: CAB Intl.

Brown, P. W.  1989.  Heat units.  Bull. 8915, Univ. of Arizona Cooperative Extension, College of Ag., Tucson, AZ.

Guzmán, I. and P.W. Bosland. 2017. Sensory properties of chile pepper heat - and its importance to food quality and cultural preference. Appetite, 2017 Oct 1;117:186-190. doi: 10.1016/j.appet.2017.06.026.

Perry, L., Dickau, R., Zarrillo, S., Holst, I., Pearsall, D. M., Piperno, D. R., et al. 2007.  Starch fossils and the domestication and dispersal of chili peppers (Capsicum spp. L.) in the Americas. Science, 315, 986-988.

Silvertooth, J.C., P.W. Brown, and S. Walker. 2010. Crop Growth and Development for Irrigated Chile (Capsicum annuum). University of Arizona Cooperative Extension Bulletin No. AZ 1529

Silvertooth, J.C., P.W. Brown and S.Walker. 2011. Crop Growth and Development for Irrigated Chile (Capsicum annuum). New Mexico Chile Association, Report 32. New Mexico State University, College of Agriculture, Consumer and Environmental Science.

Soto-Ortiz, Roberto, J.C. Silvertooth, and A. Galadima. 2006.  Crop Phenology for Irrigated Chiles (Capsicum annuum L.) in Arizona and New Mexico. Vegetable Report, College of Agriculture and Life Sciences Report Series P-144, November, University of Arizona.

Soto-Ortiz, R. and J.C. Silvertooth.  2007. A Crop Phenology Model for Irrigated New Mexico Chile (Capsicum annuum L.) The 2007 Vegetable Report. Jan 08:104-122.

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%). Variety: Deluxe (HMX2595) was seeded, then sprinkler-irrigated to germinate seed on March 20, 2024on 84 inches between bed centers. All other water 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. Treatment beds were separated by single nontreated beds. Treatments were applied with a tractor-mounted boom sprayer that delivered 50 gal/acre at 100 psi to flat-fan nozzles spaced 12 in apart. 

Spray treatments were done on 05-21-2024, 05-31-2024, 06-07-2024 and 06-14-24. Powdery mildew was first seen on 06-05-24. Please see excel file for additional details.  

Disease severity of powdery mildew (caused by Sphaerotheca fuliginea and S. fusca) severity was determined 6-17-2024 by rating 10 plants within each of the four replicate plots per treatment using the following rating system: 0 = no powdery mildew present; 1 = one to two mildew colonies on leaves  ;2 = powdery mildew present on one quarter of leaves; 3 = powdery mildew present on half of the leaves; 4 = powdery mildew present on more than half of leaf surface area ; 5 = powdery mildew present on entire leaf. These ratings were transformed to percentage of leaves infected values before being statistically analyzed.

The data in the table illustrate the degree of disease control obtained by application of the various treatments in this trial. Most treatments significantly reduced the final severity of powdery mildew compared to nontreated plants. Quintec, Merivon, Tesaris, Luna Sensation, and V6M-5-14 V gave the best disease control. Phytotoxicity symptoms were not noted for any treatments in this trial.

ANR Webinar 10/17 click link for details.

Please watch a demonstration of a spray assembly delivering herbicidal spray (blue dye) to spot spray targeted weeds. The device will be integrated with an imaging system for precision, automated / robotic weed control. Weed targets and crop plants are indicated on paper by green and yellow squares respectively. The same targeting pattern is used for simulated weeds (small plastic plants) and crop plants (white roses). Off target spray on paper is due to liquid splashing on a hard surface and is not observed on plastic weed targets. The travel speed is 2 mph and nozzle height - 5".
Click on the following demonstration link or the picture area:

Teff grass (Eragrostis tef) is originally from Ethiopia and has gained a lot of interest in Arizona. This crop is planted between vegetables and grows under different conditions and soil types. It is a fast-growing crop and can be harvested multiple times. According to the Teff Grass Crop Overview and Forage Production Guide from 2007-09 in California it was cut an average of 4 times yielding 6.89 tons/acre. The palatability to livestock is good and some report that its preferred over other traditional grass hays¹.
There is also a need for good weed control in Teff grass to satisfy buyers. 
One herbicide that was tested for postemergence broadleaf weed control and crop safety is Simplicity (pyroxulam). A 24(c) Special Local Need Registration was extended for this product. Also, another product that is successfully used in our area for broadleaf weed control is Clarity (dicamba).
 Teff is grown during the summer between other crops that could be susceptible to residue of herbicides, and it is important that any herbicide that is used doesn’t have long-term soil activity. 
We conducted a trial last summer in the Yuma Valley to evaluate the crop safety of pyroxulam, dicamba and other herbicides. Our results for pyroxulam were consistent with the injury observed in the visual ratings obtained by B.J. Hinds-Cook, D.W. Curtis, A.G. Hulting and C.A. Mallory-Smith with a 10% recorded².
Also, efficacy for the control Purslane (Portulaca oleracea) was evaluated. The following chart shows data obtained.

Results of pheromone and sticky trap catches can be viewed here.
Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 15, July 24, 2024

Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:             
CEW moth counts increased in Roll and Yuma Valley; about average to previous years.
 
Beet armyworm:          
BAW moth counts increase in Tacna and Wellton; comparable to previous summers.
 
Cabbage looper::          
Cabbage looper numbers are low consistent with previous years and higher temperatures.
 
Diamondback moth:      
DBM moths were not caught in any trap; average for this time of the year.
 
Whitefly:                      
Adult movement continues to increase consistent with disking of late melon fields and volunteers.
 
Thrips:                          
Thrips adult activity continues to decline, comparable to mid-summer.
 
Aphids:                        
Aphid movement is absent and consistent with what we typically see during the summer.
 
Leafminers:                  
Adult activity about average for early July.