May 5, 2021Summer Sanitation Is Important as Ever
To contact John Palumbo go to: jpalumbo@ag.Arizona.edu
Clovers can be very difficult to control weeds here, but it is also a major crop and common ornamental. Clovers can survive under poor growing conditions and are not controlled with glyphosate and seem to get worse every year. There are more than 50 types and 300 species of clover and they can be easily misidentified. They are all in the legume (Fabracea) family and can use a bacterium (rhizobium) in the soil to convert nitrogen in the atmosphere to a form that they and other plants can use for fertilizer. There are only 4 or 5 clover species that are agricultural pests here. The ones we get the most questions on are white and yellow sweet clover. These are in the Melilotus family. White sweet clover (Melilotus albus) is tall for a clover and can get 3 to 5 foot in height. The leaves are thinner than most clovers and this difficult to control weed lives at least 2 years and sometimes longer. Glyphosate and most of the contact herbicides do not control it. The plant growth regulator herbicides work best. Yellow sweet clover (Melilotus officinalis) is less common here. The flowers are yellow, and it is not as tall and vegetative as white sweet clover. Yellow is more common at higher elevations. California burclover (Medicago polymorpha) and Black medic (Medicago lupina) are in the same genus as alfalfa and are more of a problem in landscapes, parks and golf courses than in agricultural fields here. They do not grow upright and spread below the crop or turf. The true clovers are in the Trifolium genus and include white and strawberry clover. These creep along the ground and root at the nodes of the stem. These are more of a urban landscape weed and not considered an agricultural problem. Creeping woodsorrel or Oxyalis looks like a clover but it is not related. It is a turf weed that spreads rapidly along the ground and can live for several years. Preemergent herbicides are effective against all these clovers before they become established. The postemergence herbicides that are most effective in controlling these clovers are the plant growth regulators. Contact herbicides and glyphosate are generally ineffective.
Bindu Poudel, Martin Porchas, and Rebecca Ramirez
Yuma Agricultural Center, University of Arizona, Yuma, AZ
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%). Spinach ‘Revere’ was seeded, then sprinkler-irrigated to germinate seed Jan 13, 2019 on beds with 84 in. between bed centers and containing 30 lines of seed per bed. All irrigation water was supplied by sprinkler irrigation. Treatments were replicated four times in a randomized complete block design. Replicate plots consisted of 15 ft lengths of bed separated by 3 ft lengths of nontreated bed. Treatments were applied with a CO2 backpack sprayer that delivered 50 gal/acre at 40 psi to flat-fan nozzles.
Downy mildew (caused by Peronospora farinosa f. sp. spinaciae) was first observed in plots on Feb 12 and final reading was taken on March 20, 2020. Spray treatment were applied on February 14,19, 24, and 28 of 2020(see table). Disease severity was recorded by determining the percentage of infected leaves present within three 1-ft2 areas within each of the four replicate plots per treatment. The number of spinach leaves in a 1-ft2 area of bed was approximately 300.
The data (found in the accompanying table) illustrate the degree of disease reduction obtained by applications of the various tested fungicides. Two treatments Torac/Revus rotation, and Torac, provided the most effective disease control.
The autonomous agricultural robot industry is an incredibly fast-moving space. Startups, established companies and academic researchers are continuously putting forth new ideas and products. It’s hard to keep up with. In November of 2020, Future Farming (Misset Publisher, BV, Doetinchem, Netherlands) published a Field Robots Catalogue that provides a comprehensive overview of the state of autonomous ag robots. The article provides brief summaries of 35 autonomous ag robots that are currently commercially available. Along with a brief paragraph about what each robot does, the article presents information about how many robots from a particular manufacturer are actively being used, the cost of the machine, and links to a video of the device in action. Most of the robots are for weed management in vegetable crops. Kill mechanisms range from spot spraying to mechanical weed removal to electrocution. Several of the robots featured are applicable and relevant to Arizona vegetable production, and some are currently operating in the U.S. If you’re interested in ag robots and want to get up to date, this article is an excellent resource and quick read. The article can be found at the link provided below.
Title: Future Farming Field Robots Catalogue
Publisher: Misset Publisher, BV, Doetinchem, Netherlands.
The Yuma County Leaf Wetness Network remains in place for the 2018/19 vegetable season. Growers and PCAs may access information generated by the network by entering the following internet address: http://18.104.22.168:460
Upon entering the address above, you will be transferred to internet page that provides a series of tabs at the top of the page. Simply click on the tabs to access the information of interest.
Area wide Insect Trapping Network VegIPM Update, Vol. 11, No. 21, October 14, 2020
Results of pheromone and sticky trap catches can be viewed here.
Corn earworm: Moth activity is above normal for early October ad has been steadily increasing since mid-September, particularly in Dome Valley and south Yuma Valley.
Beet armyworm: Moths remain active throughout the desert, especially in Texas Hill and Dome Valley growing areas.
Cabbage looper: Cabbage looper activity remains unusually low for early October, likely a result of unusually hot weather. Larvae just starting to show up in some fields.
Whitefly: Adult movement has been about average for this time of year. Activity highest in Wellton and Roll near fall melons.
Thrips: To date, thrips activity has been seasonably low at all trap locations; most activity found in Bard. Numbers beginning to slowly trend upward
Aphids: Aphids have been caught in only one trap thus far (Bard). Normal for this time of year. Still early, anticipate they will begin to show up in heavier numbers in mid-late October.
Leafminers: Adult activity below normal for September, but moderate numbers caught in Wellton and south Gila Valley in areas where cotton was recently harvested and disked under.