Everything we eat and much of what we are surrounded by in our daily lives have a common base from water and the production of green plants. Anything made of carbon, even if the immediate source of carbon is a petroleum-based product, has an original derivation that starts with green plants and water.
Green plants perform the miraculous process of photosynthesis that captures light energy from the sun to combine with water (H2O) taken up from the soil through the root system, carbon dioxide (CO2) from the air, forming a simple 6-carbon carbohydrate compound (C6H12O6), and liberating free oxygen (O2) into the atmosphere.
Photosynthesis involves a complex system of biochemical reactions, but the fundamental photosynthesis process can be reduced to very simple terms as outlined in Figure 1.
Figure 1. Basic photosynthesis reaction. (Source: Collegedunia).
Figure 2 offers a little more detail in the photosynthetic process and there is still more to the story. But the essentials are outlined in Figures 1 and 2.
Figure 2. Connections between photosynthesis and plant respiration.
The process of taking CO2 from the atmosphere and “fixing” the carbon in a larger and more complex form as a basic carbohydrate (simple sugar compound) is referred to as “carbon fixation” and green plants provide most of this primary function in the earth terrestrial, or land-based ecosystems.
Carbon fixation is conducted by organisms containing chlorophyll and green plants do most of this work. There are also some species of algae and cyanobacteria that can fix carbon from the atmosphere. But green plants, using energy from the water and water from the soil are the real workers in our world in this regard.
Water is essential in this process of fixing carbon through photosynthesis. In fact, six units of water are required for every unit of carbohydrate that is produced (Figure 1).
Additional water is used by the plant in the transpiration process, which is the movement of water from the soil through the root system, through the conductive tissues of the plant. This provides for good cellular hydration and biological function. In the transpiration process water moves out of the plant and escapes into the atmosphere as gas through the stomates, which are small openings in the underside of plant leaves (Figure 3).
Figure 3. Plant transpiration. Source: Premium Vector
Through this process of photosynthesis, water and green plants serve as the backbone of all terrestrial life. These are fundamental facts and critical functions that we manage in crop production systems. Essentially, every field with a green crop growing is a photosynthetic factory and water is always an essential component.
Consumers directly benefit from the water used to produce the crops with all the fruits and vegetables that come from them. Healthy animals require good food, which all comes from plants, i.e., alfalfa. Everything we consume has a significant water footprint and much of that involves supporting plant photosynthesis.
The inescapable fact is that we need the plants, and the plants need water to grow and produce.
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.govInterested in the latest developments in automated weeding machines? There are a couple of opportunities at the upcoming 2024 Southwest Ag Summit to stay up to date. One is the “Ag Tech: Innovations in Weed Control Technologies” breakout session where university experts and cutting-edge innovators will provide updates on the latest advances in AI, laser weeding, high precision smart spot sprayers, robotic/automated weeders and band steam (agenda below). The session will be held Thursday, February 22nd from 1:30-3:30 pm at Arizona Western College (AWC) in Yuma, AZ.
The other is the Southwest Ag Summit Field Demo on February 21st, where several of these technologies and other state-of-the-art automated weeders will be demonstrated operating in the field. The Field Demos will also be held at AWC. Breakfast will be served at 7:00 am and demonstrations begin at 8:00 am.
For more information about the Southwest Ag Summit, visit https://yumafreshveg.com/southwest-ag-summit/.
Fig. 1. Agenda for the “Ag Tech: Innovations in Weed Control Technologies”
educational session at the 2024 Southwest Ag Summit. The session will be held
Thursday, February 22nd at Arizona Western College, Yuma, AZ.
Fig. 2. 2024 Southwest Ag Summit Field Demo agenda. The event will be held at
Arizona Western College in Yuma, AZ.
This is lettuce..what do you think?:
send your comments here: marcop@ag.arizona.edu
We Need Your Input!
The Environmental Protection Agency (EPA) is seeking public comment on its Draft Herbicide Strategy Framework to protect threatened and endangered species. The Strategy outlines proposed mitigations on agricultural herbicide use that could have significant impacts on production of field crops and specialty crops in the lower 48 states.
The Arizona Pest Management Center will submit comments to EPA to communicate the challenges and potential impacts of the proposed Strategy on our agricultural industries, but we need your help.
We need input from growers, applicators, pest control advisors, registrants and others on the feasibility of EPA’s proposed mitigations for Arizona production systems. If you are concerned about EPA’s proposed changes and willing to share your knowledge of what works in Southwest agriculture, your input could help make a difference.
Please consider responding to our online survey by clicking the link below. The survey takes around 12 minutes and is completely anonymous. The data you provide will only be used in aggregate to communicate local farming practices and concerns related to herbicide mitigations to the EPA. Taking this survey is also a good way to learn more about EPA’s specific proposed changes. Please respond by October 19.
Survey Link: https://uarizona.co1.qualtrics.com/jfe/form/SV_1QUBcXiIVgjFDHE
Thank you!
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.
