I want to take this opportunity to express my gratitude to the University of Arizona (UA) Vegetable Integrated Pest Management (V-IPM) Team consisting of Marco, John, Barry, Bindu, and Mark for inviting me to join the team and provide an agronomic component. This is also a good opportunity to offer some background on myself and my connection to the V-IPM realm.

I was first exposed to the concepts of IPM in crop production systems while I was an undergraduate student in agronomy at Kansas State University in the early 1970’s. Following graduation 1976, I began working as an agronomist-crop consultant in the irrigated crop production systems on the high plains of southwestern Kansas. In this capacity I was responsible for contracting 10,000-15,000 acres per year with the duty of providing useful crop production and management input to the growers on a continual basis and very importantly for protecting the crop from pests (insects, weeds, and diseases).

I learned very quickly in my first year in the field as a young agronomist-crop consultant that I could do an excellent job of assisting in the planning and management of basic agronomic inputs such as variety selection, planting management, soil fertility, tillage, rotations, etc. But if I was going to survive and do well in that job, I needed to learn how control crop pests effectively. The use of IPM practices was very new at that time and the crop consulting group I was working with were employing IPM practices in the field. The IPM approach worked best for effective pest control and gave us that capacity to protect the crop and it was the best route for economic profitability, plus we could see the environmental benefits, even the late 1970s. The farmers we worked with were somewhat dubious at first but began to see this working and readily embraced the use of IPM.

In the five seasons that I worked on the southern high plains in this capacity, I developed an appreciation for good programs in applied research and Extension education. As crop consultants, we appreciated the work provided by the scientist from Kansas State, Oklahoma State, Nebraska, and Colorado State Universities for developing and communicating the thresholds and control methods for the important crop pests in our region. They gave us the basic tools and we took that to the field, refined it, and made it work most effectively. It was an important partnership between the land-grant universities and our work in the crop production industry.

As a result of those experiences, I was motivated to return to graduate school in the Agronomy Department at Oklahoma State University with a major area of focus in soil-fertility and plant nutrition.

In January 1987, I interviewed, was offered, and accepted a position at the UA in Tucson, Arizona as an Extension Agronomist-Cotton (aka Cotton Specialist). Cotton production in 1987 was robust and widespread throughout southern Arizona and IPM was being introduced by UA personnel, but the cotton community was dubious, to say the least. In 1990 we were hit with horrendous pink bollworm (Pectinophora gossypiella, Saunders) infestations in cotton fields throughout the state and then whitefly populations (Bemisia tabaci Genn) rapidly increased to very damaging levels in 1991 and 1992. Working with an excellent team of UA Extension colleagues and the regional cotton industry, we were able to bring some good IPM practices, including important cultural practices, into our systems. New scientists like Drs. John Palumbo and Peter Ellsworth were hired and the IPM capacities in our UA programs significantly improved with their input and leadership.
Today, the IPM effort in Arizona is one of the very best in the country and the agricultural industry is among the most progressive as well. The V-IPM team stands out as one of the very best in this region or anywhere and I certainly appreciate the opportunity to work with this outstanding group and the vegetable crop production industry. Having some agronomic input to the V-IPM is good integration.

I am seeking samples of downy mildew on lettuce from around Yuma County to support the Michelmore Lab and their ongoing efforts to help characterize the downy mildew populations of the United States. The Michelmore Lab has led the charge on a survey of Bremia variants since 1980 and has been instrumental in demystifying the gene-for-gene nature of lettuce resistance to downy mildew.

Their group invites growers across the United States to submit downy mildew infected plant samples, which are then used to culture the Bremia on live host plants. The team then inoculates a panel of lettuce varieties carrying known resistance genes to determine the race of each isolate they receive. Identifying which races occur in which specific fields is essential to guiding the breeding of new resistant cultivars and maximizing the effectiveness of host-based genetic disease management. The data obtained from these tests are also used to designate new Bremia races through the International Bremia Evaluation Board.

Your contribution will help breed better lettuce for Yuma. This means less breakdown of resistance in the field, and better yields for Yuma growers. To facilitate these submissions the Yuma Plant Health Clinic will be setting up a separate drop-off point and submission sheet for downy mildew sample submissions in the same hallway we use for standard plant diagnostic submissions. The drop-off point will be clearly labelled and consist of a chest-style refrigerator and printed copies of the submission form. It is vital to keep these samples cool so they remain viable for future inoculations, so please place your samples inside of the refrigerator before you leave.

Shipping will be handled by the clinic. All we ask is that you fill out the submission form as completely as you can. An example of the questions that are asked in that form so you can prepare ahead of time can be found HERE . 

Vol. 12, Issue 7, Published 4/7/2021

Over the last several years, there has been a tremendous amount of research activity towards the development of autonomous agriculture vehicles. A quick internet search will reveal over 50 companies or university research groups working in this space. A question I get often from groups developing such platforms is “What is a good agricultural application for our lightweight “robot”?”. It’s a great question, and for Arizona vegetable production, it’s also one that I’m not sure I have a satisfying answer for.

The calls I get regarding autonomous robots are mostly related to automated weeding applications. Automated weeding machines are commercially available, but their adoption has been limited not because of labor costs for tractor operation, rather it is the lack of the development of a functional and cost-effective means for identifying and removing weeds.

For decades, researchers have been attempting to develop sensing systems that are able to reliably detect weeds. Techniques such as 2-D and 3-D color imaging, x-rays, hyperspectral sensing and artificial intelligence have been tried (Slaughter, 2014; Bender et al., 2020). The best performing systems provide about 96% accuracy, meaning that 4% of the crops plants are identified as weeds and would be destroyed by the weeder. For high value vegetable crops like lettuce with gross revenues of roughly $10,000 per acre, killing 4% of the crop equates to $400 per acre of losses. Economically, this does not make sense as hand weeding labor costs are typically $300 per acre or less. The other main issue is that current automated weeding technologies are not highly precise and provide only partial control. Our studies with these types of machines have shown that these systems remove only about 1/3^rd of the in-row weeds (Lati, et al., 2016) and a follow up hand weeding operation is often necessary. To be highly cost effective, elimination of the hand weeding step is needed.

In short, my recommendation to research groups asking about applications for autonomous robots is that their time and technical skills would best be served developing reliable crop/weed differentiation systems and a technique to remove a very high percentage of weeds.

References
Bender, A., Whelan, B. & Sukkarieh, S. 2020. A high‐resolution, multimodal data set for agricultural robotics: A Ladybird's‐eye view of Brassica. J. Field Robotics. 37(1): 73-96.

Lati, R.N, Siemens, M.C., Rachuy, J.S. & Fennimore, S.A. (2016). Intrarow Weed Removal in Broccoli and Transplanted Lettuce with an Intelligent Cultivator. Weed Technology, 30(3), 655-663.

Slaughter, D.C. The biological engineer: Sensing the difference between crops and weeds. Autonomous robotic weed control systems: A review. Computers and Electronics in Agriculture 61(2008): 63-78.

When known weedy fields are ready to plant and labor is expected to be short, it is tempting to use all the preplant herbicides that are available. In lettuce, there are three preplant herbicides available and it is not uncommon to use 2 and occasionally all 3 on the same crop. All three of these herbicides use the same mode of action to kill weeds. There are slight differences between them but they all either stop or disrupt cell division in the roots and or stems of the weeds. They are normally safe to lettuce unless the crop is stressed or the rate, timing or placement are poor. The rationale for using multiple preplant herbicides in lettuce is often to broaden the weed control spectrum or guard against misses caused by misapplication or environmental conditions. There are some hazards, however, that sometimes outweigh the benefits. Potential crop injury is increased. All 3 use the same mode of action and the chance of injuring developing crop roots is compounded. Sometimes herbicides are added that contribute nothing but potential injury to the mix. If you look at the following chart you can see that many weeds are controlled by Kerb, for instance, that are not controlled by Balan or Prefar. Why add them? All three control grasses, goosefoot and purslane. If environmental conditions and applications are optimal it is often possible to use only one. Herbicides are much less expensive than labor, but it is possible to overdo it and cause more problems and expense.

 

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 3, Feb 7, 2024
 
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:             
CEW moth counts increased in the Rol and Dome Vallley areas, above average for this time of year. 
 
Beet armyworm:         
Trap counts low; lower than average compared to previous years.
 
Cabbage looper:           
Cabbage looper counts increased in most traps and about average for this time of season.
 
Diamondback moth:       
DBM moths counts increased in most areas. About average for this time of the year.
 
Whitefly:                       
Adult movement negligible, typical for mid-winter. 
 
Thrips:                          
Thrips adult counts remain low, likely in response to rainfall in late December. Currently, numbers are below average compared with previous years.
 
Aphids:                        
Aphid movement increased significantly in the past two weeks, particularly in North Yuma and Gila Valleys. Highest numbers we’ve seen in 11 years.
 
Leafminers:                   
Adults remain low in most locations, average for January.