Nov 15, 2023Field Sanitation Important for Avoiding Spring Pest Problems
Yogi Berra once retorted “You can observe a lot by just watching”
To contact John Palumbo go to: jpalumbo@ag.Arizona.edu
Yogi Berra once retorted “You can observe a lot by just watching”
The drought-related pressures on the Colorado River system that have been impacting the entire basin and region for 23 years have slackened briefly due to the wet winter in 2023 that included a good snowpack in the mountains, better rainfall throughout the basin, and improved flows into the river. The current water level at Lake Mead on Hoover Dam is 1,068.25 ft. above sea level on 3 January 2024. That level is 160.75 ft below full pool of 1,229.00 ft. (Figure 1).
In mid-December 2023 representatives from each of the seven Colorado River Basin states met in Las Vegas, NV during the annual Colorado River Water Users Association conference. The focus of current discussions among the basin states is to negotiate a new compromise for the guidelines of use under conditions of water shortage. These new guidelines will go into place at the end of 2026. The immediate goal is to draft proposals by March 2024.
The negotiations are incentivized by having the opportunity for the post-2026 guidelines being developed by the basin states themselves as opposed to litigation or legislation. A major concern driving this process among the basin states that basin state representatives should be able to do this better than turning the process over to people and entities that have less direct familiarity with the situation and no real “skin” in the game.
The 1963 decision by the Supreme Court of the United States in of the Arizona v California case directed the federal authority on the management of the Colorado River to the Department of the Interior and the Bureau of Reclamation (BoR). However, the basin states have the chance to negotiate their future management plans on the Colorado River. If they fail to do so in the allotted time, the process will be managed by the federal government.
The basic water budget challenge is based on the following basic statistics:
Some notable progress is being made for conservation of Colorado River water with agreements among lower basin states and tribes that will conserve more than 1.5maf/year through 2026. For example, California water agencies have recently agreed to conserve up to 643,000 acre-feet/year through 2025. The Quechan Indian Tribe has reached an agreement with federal water managers to save up to 39,000 acre-feet/year through 2025. Arizona has agreed to conserve up to 348.00 acre-feet/year through 2026. All these temporary agreements are being supported with federal funding.
With agriculture responsible for 70% of the diversions on the Colorado River, these negotiations are extremely important for the future of agriculture in this region and our capacity to support high population densities that are now common and rapidly growing.
These types of negotiations are certainly challenging in dealing with a limited water supply and a lot of demand. There are many competing interests involved. Yet, we are confident that the representatives we have will be able to work this out and come to a set of functional agreements.
As the lettuce plants start to grow and get bigger in the field, you might start seeing the symptoms of bacterial soft rot. Though it rarely takes down the whole field, the symptom are not so pleasant. Bacterial soft rot in lettuce can occur in the field as well as post harvest.
It is caused by several types of bacteria, but primarily subspecies and pathovars of Erwinia caro-tovora and E. chrysanthemi. Other bacterial species that cause soft rot include Pseudomonas cichorii, P. marginalis, and P. viridiflava. They have a wide host range host range and includes genera from nearly all plant families
In lettuce fields, the symptoms are observed close to the harvest time. The tissue, mostly around inside the head of head lettuce softens and becomes mushy or watery. Slimy masses of bacteria and cellular debris frequently ooze out from cracks in the tissues. Decaying tissue, which may be opaque, white, cream-colored, gray, brown, or black frequently gives off a characteristically putrid odor. The odor is caused by secondary invading bacteria that are growing in the decomposing tissues.
The bacteria overwinter in infected fleshy tissues in storage, in the field, garden or greenhouse, in the soil (especially in the rhizosphere around the roots of many plants), and on contaminated tools, equipment, containers, and in certain insects. The bacteria enter primarily through wounds made during planting, cultivating, harvesting, grading, and packing and through freezing injuries, insect and hail wounds, growth cracks, and sunscald. They may also follow other disease-producing organisms. Uninjured tissues may become infected when the humidity approaches 100 percent or when free moisture is present. Rains, poorly drained or waterlogged soils, and warm temperatures favor infection in the field, as does high humidity in storage or transit.
The bacteria multiply rapidly by dividing in half every 20 to 60 minutes under ideal conditions at temperatures between 65° and 95° (18° and 35°C). Minimum temperatures for development is between 35° and 46°F (2° and 6°C); and maximum between 95° and 105°F (35° and 41°C.
The bacteria are spread by direct contact, hands, tools and farm machinery, insects, running or splashing water, contaminated, water in washing vats, clothing, and decayed bits of tissue.
Promptly and carefully destroy infected plants. Maintain well aerated field, avoid close planting and overhead irrigation.
To minimize post harvest losses, avoid mechanical injusry after harvest, packing and shipping. Do not pack produce when wet. Store and ship produce at temperatures near 4°C (39°F).
Time flies. February is right around the corner and that means it is farm equipment/ag trade show season. Upcoming regional events include the World Ag Expo, Tulare, CA, February 13-15, the Southwest Ag Summit, Yuma, AZ, February 20-22, and AgroBaja, Mexicali, Mexico, March 7-10. If you are interested in the latest ag tech and farm machinery, all are outstanding events and well worth attending. For more information, click on the links below.
Fig. 1. Upcoming farm equipment/ag trade show events: World Ag Expo, Tulare,
CA, February 13-15, 2024 theSouthwest Ag Summit, Yuma, AZ, February 20-
22,2024 and AgroBaja, Mexicali, Mexico, March 7-10, 2024.
Before making decisions for weed control it’s imperative to have a proper identification of the plant species. There are two names for plants:
The common name, which is a name that people come up with in a certain region to describe a particular weed and it varies by region and therefore can be confusing. Then we have an exact scientific name for each species that is based in the binomial nomenclature system started by Carl Linnaeus in 1753. This binomial (or two term) system includes the genus and the species, which is used worldwide1.
Some very close species from the same family can be controlled by the same product but occasionally their herbicidal susceptibility varies. Such is the case of Chenopodium murale (goosefoot) and Chenopodium album (lambsquarter) two very close and similar species. A product like Pursuit (Imazethapyr) has good activity on goosefoot but can’t control lambsquarters. With accurate identification in a mixed population, you would be able to determine what strategy to use or select the herbicide that would control both species.
There are about 75 weeds most common in Arizona and are included in the PCA2 study guide, but many other species could be introduced to the State and complicate our crop production systems. Two great tools for weed identification are the books “An Illustrated Guide to Arizona Weeds” that lists 172 species, and “Weeds of California and Other Western States” which has at least one photograph of 735 weeds.
Another weed identification tool is the book “Weeds of the West”.
Additionally, there are many phone applications that can be used as identification tools such as “id weeds”, “PlantNet”, “PictureThis”, “iNaturalist”, “Seek”, “PlantSnap” and “LeafSnap”. When we have problems with weed ID we contact the UA herbarium.
Thank you for sending samples for Weed ID to the IPM Team it is always a learning experience.