Early Sunday morning, 11 May 2025 Dr. John Palumbo passed away at his home in Yuma, AZ. John was an excellent scientist and educator, a lifelong student who truly enjoyed good work and a full life. John was also a very good friend and colleague, not only to me but to the many with whom he worked and lived. We mourn his passing and miss him deeply.

I first met John in 1990 when he joined the faculty at the University of Arizona (UA) as an Assistant Professor and Extension Specialist in Entomology and Integrated Pest Management (IPM) based at the Yuma Agricultural Center (YAC). He came very highly recommended by Drs. Theo Watson and Leon Moore, who were research and Extension entomologists and former mentors of John’s when he was an undergraduate and graduate student at the UA.

John did his Ph.D. work at Oklahoma State University (OSU) under the direction of Dr. Larry Crowder, who had been on the UA faculty in entomology prior to moving to OSU. I am originally from Oklahoma and went to graduate school at OSU in agronomy and soil science. I used to jokingly tell John that having spent some formative years in Oklahoma was probably his time of refinement and saving grace.

John was a perfect fit for the position at the UA and at YAC; he was highly intelligent with an excellent background. Most importantly, it was very clear that he was enthusiastic about his opportunity, and he really wanted to do the work necessary. He truly loved his work, and he did it very well with passion and commitment.

John had an outstanding work ethic, he was a man of good character, and his integrity was exceptional. John was a practical realist, and even though we could both see and comment on the imperfections in the world around us, he did not whine or complain about things that could have been better. He was always an optimist, and he did the best with what he had, appreciated his opportunities, and he consistently did a great job with it. He was a model as a professional and as a good person. He had confidence in himself, but he was humble, and he always treated people with respect and dignity. Very importantly, John had a great sense of humor, and I could always count on that with him.

In 2018 John was diagnosed with stage 4 lung cancer. That was not a good prognosis, but John faced it with dignity and grace. John had access to some new drugs that helped give him a good quality of life that he sustained for seven years. In the past seven years he has been productive, worked hard, and he has had fun doing so. He did not dwell on the negative but always emphasized the positive.

John was an avid reader and we both shared an interest in history, particularly American history, including the Civil War. Many of our conversations centered around these common interests and we shared many good reading references.

In my readings I have also enjoyed the writings of Ernest Hemingway. Hemingway emphasized the value and benefits of living a robust life and spending time outdoors in nature. Many of his characters demonstrated a strong way of living and strength in facing the end of their lives. In one of Hemingway’s books (Across the River and Into the Trees) he offered a recounting of the passing of General Thomas “Stonewall” Jackson on 10 May 1863 following his injuries at the Battle of Chancellorsville.

Dr. McGuire, the attending physician, confirmed to Jackson what his wife had conveyed earlier regarding McGuire’s projection of his impending death that day. Jackson’s response after thinking for a moment was that the day was Sunday and he felt that Sunday was a good day to die. After passing in and out of delirium, the last he said was “Let us cross the river and rest in the shade of the trees.”

John Palumbo passed away on a Sunday in May. He has crossed the river and is now resting in the shade of the trees.

At events and in the halls of the Yuma Agricultural Center, I’ve been hearing murmurings predicting a wet winter this year…

As the Yuma Sun reported last week, “The storms of Monday, Aug. 25 [2025], were the severest conditions of monsoon season so far this year in Yuma County, bringing record-rainfall, widespread power outages and--in the fields--disruptions in planting schedules.”

While the Climate Prediction Center of the National Weather Service maintains its prediction of below average rainfall this fall and winter as a whole, the NWS is saying this week will bring several chances of scattered storms.

These unusually wet conditions at germination can favor seedling disease development. Please be on the lookout for seedling disease in all crops as we begin the fall planting season. Most often the many fungal and oomycete pathogens that cause seedling disease strike before or soon after seedlings emerge, causing what we call damping-off. These common soilborne diseases can quickly kill germinating seeds and young plants and leave stands looking patchy or empty. Early symptoms include poor germination, water-soaked or severely discolored lesions near the soil line, and sudden seedling collapse followed by desiccation.

It is important to note that oomycete and fungal pathogens typically cannot be controlled by the same fungicidal mode of action. That is why an accurate diagnosis is critical before considering treatments with fungicides. If you suspect you have seedling diseases in your field, please submit samples to the Yuma Plant Health Clinic or schedule a field visit with me.

National Weather Service Climate Prediction Center: https://www.cpc.ncep.noaa.gov/

National Weather Service forecast: https://forecast.weather.gov

PBS News recently did a story on the importance of Yuma’s winter vegetable production and the pressures the Western US is facing due to water scarcity. The story features insights from local growers Matt McGuire, JV Smith Companies and Jon Dinsmore, Dinsmore Farms, as well as Arizona Department of Agriculture Director, Paul Brierley. The report is well done, covering the basics of Yuma agriculture and the water shortage issues the industry is facing. It’s a quality piece, worth a listen.

Check it out by clicking here or on the image below.

Fig. 1. PBS NewsHour: “Arizona Farmers Forced to Adapt as Main Water Source Dries Up” story. (Photo Credits: PBS News)

Wanted to share the following weed germination calendars now that the season has begun. Some summer weeds withstand part of the winter and some winter annuals the summer, so these charts are general guidelines. We hope this helps for making management decisions in your operation.

Aphids are considered the most difficult to control insect pests in organic vegetables due to the lack of effective bioinsecticides as well as their ability to hide within plant structures. For instance, lettuce aphids normally hide in the head or heart of lettuce, making them difficult to reach by insecticide treatment or natural enemies. It is important to adopt other methods, such as nitrogen and water management, for additional aphid suppression.

As sap-sucking insects, aphids depend on the nutritional content of the sap ingested from the plant hosts for proper growth and development. Nitrogen availability is one of the most important factors in the development of aphid populations. Thus, limiting your nitrogen application to the optimum amount required for your crops is good practice for maintaining your aphid population below damaging level. Additionally, the use of slow-release (minimizing the risk of nutrient deficiency or excess) nitrogen fertilizer can be beneficial for aphid control. On the other hand, excess of nitrogen will make your crops a superfood for aphids. This accelerates the growth, development, and reproduction of the pests, reduces their generation time, and results in an increase in the number of generations and density during the cropping season. Excess of nitrogen particularly affects aphids on host crops such as lettuce, wheat, and sorghum. In some situations, high nitrogen levels in plant tissue can decrease resistance and increase susceptibility to aphids’ attacks. Applying the optimum amount of nitrogen fertilizer can tremendously help to manage aphids. In addition to pest management, effective fertilizer usage can also result in economic and environmental benefits.

Selected References:
1- Altieri, M. A., C. I. Nicholls, and M. A. Fritz. Manage insects on your farm: a guide to ecology strategies. SARE. https://www.sare.org/resources/manage-insects-on-your-farm/

2- Aqueel, M. A., and S. R. Leather. 2011. Effect of nitrogen fertilizer on the growth and survival of Rhopalosiphum padi (L.) and Sitobion avenae (F.) (Homoptera: Aphididae) on different wheat cultivars. Crop Protection. 30:216-221.

3- Bal, R., M. Groshok, and Y. Jama. 2024. Effects of nitrogen and potassium-based fertilizers on green peach aphid and abundance and arugula condition and growth. The Scientist. 6:1. https://journals.mcmaster.ca/iScientist/article/view/2931

4- Sinha, R., B. Singh, P. K. Rai, A. Kumar, S. Jamwal, and B. K. Sinha. 2018. Soil fertility management and its impact on mustard aphid, Lipaphis erysimi (Kaltenbach) (Hemiptera: Aphididae). Cogent Food & Agriculture. 4: 145094.

5- Xia, C., W. Xue, Z. Li, J. Shi, G. Yu, and Y. Zhang. 2023. Presenting the Secrets: exploring endogenous defense mechanisms in chrysanthemums against aphids. Horticulturae. 9: 937. https://doi.org/10.3390/horticulturae9080937

Supplying the optimum amount of water to your crop is also very important for effective pest control. Water availability around plant roots increases nitrogen absorption. Additionally, with high water availability, there is an increase in phloem pressure, making food more accessible to sap-sucking insect pests. Supplying the required amount of water using appropriate irrigation methods and irrigation scheduling can be beneficial for pest management. Although these practices will not completely prevent infestation of aphids, they can surely play a role in reducing the density of aphid populations on your crops.

I had the privilege of knowing Dr. John Palumbo for nearly a year, and in that short time, he left a lasting impact on me both personally and professionally. From the moment I joined the Yuma Agricultural Center, John welcomed me with genuine generosity, readily offering his help and connecting me with key stakeholders in the Yuma area. Despite the demands of his extensive and impactful program, his office door was always open for any questions I had. Just a few weeks ago, I was attending a workshop in Imperial, California, hosted by the University of California Cooperative Extension. During the IPM session, I believe his name was mentioned more than ten times, underscoring the depth and influence of his research, findings, and recommendations. John was a true leader of the agricultural community in the Southwest, and his contributions will continue to shape the field for years to come. He leaves behind a legacy of excellence, mentorship, and service. Thank you, Dr. John Palumbo, for everything you have done. You will be deeply missed and fondly remembered.

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

Corn earworm: CEW moth counts down in most over the last month, but increased activity in Wellton and Tacna in the past week; above average for this time of season.

Beet armyworm: Moth trap counts increased in most areas, above average for this time of the year.

Cabbage looper: Moths remain in all traps in the past 2 weeks, and average for this time of the season.

Diamondback moth: Adults decreased to all locations but still remain active in Wellton and the N. Yuma Valley. Overall, below average for January.

Whitefly: Adult movement remains low in all areas, consistent with previous years.

Thrips: Thrips adults movement decreased in past 2 weeks, overall activity below average for January.

Aphids: Winged aphids are still actively moving, but lower in most areas. About average for January.  

Leafminers: Adult activity down in most locations, below average for this time of season.