May 5, 2021Summer Sanitation Is Important as Ever
To contact John Palumbo go to: jpalumbo@ag.Arizona.edu
Oxyfluorfen,(Goal and Galigan) has become a popular and effective herbicide for use on cole crops even though it was first registered in the 1980’s. Oxyfluorfen is a contact herbicide with the same mode of action as Chateau, Aim, Shark, Gramoxone, Paraquat , Sharpen and ET. They are all PPO Inhibitors that rupture cell membranes. Carfentrazone (Aim, Shark), ET and Paraquat (Gramoxone), are effective only as postemergence applications to small weeds, Sharpen and Goal are effective both preemergence and early postemergence and Chateau is used only preemergence but can cause severe crop injury if mixed with a surfactant. The only one of these that is registered for cole crops is Oxyfluorfen (Goal, GoalTender, Galigan). It does not make sense for a contact herbicide to be used on weeds that have not emerged. The way this works is that a barrier is created with the herbicide on the surface that kills the seedling weeds as they come in contact with it. It is important not to disturb this barrier or the weeds will not be affected. Oxyfluorfen (Goal) is an herbicide that defies reason in other ways as well. It normally adheres strongly to the soil and has very low water solubility. It is well known, however, that Goal can lift off of the surface and cause crop injury. When this happens, it is evaporating or going from a liquid to a gas and this is unaffected by its solubility or adsorption. It also works well when chemigated through a sprinkler system. You would think that it would wash off, but it works well with less crop injury when chemigated. Chemigation is registered for onions only but it works well with cole crops as well. It only takes half as much (4 ounces) and is safer to the crop when chemigated. It is best to apply it about 2/3 of the way through the sprinkler run to keep it in place and flush the system.
Damping off is a common problem in spinach. This season we have observed the occurrence of the disease from Imperial valley, to Yuma and all the way to Wellton.
Symptoms of damping‑off and root rot consist of poor seed germination, preemergence death of seedlings, postemergence death of newly emerged seedlings, stunted plants, yellowed lower leaves, general poor growth, wilting, and eventual collapse and death of older plants. The upper taproot may be girdled by a necrotic lesion, or the tip of the taproot may be necrotic. In severe cases, nearly all roots may be girdled or rotted off. Damping-off is problematic in spinach production areas throughout the world. Severity is influenced by cultivar, soil texture, irrigation, and pathogen populations. Severe damping-off is associated with clay or poorly draining soils with a history of frequent spinach production. While all stages of spinach can be infected by root rot organisms, newly emerging plants and young seedlings are very susceptible.
Symptoms are more prominent in areas with poor drainage. These spinach problems are caused by a complex of pathogenic soil fungi that include one or more of the following: Fusarium oxysporum, Pythium (several species), and Rhizoctonia solani. These fungi are present in most soils and can get aggressive and cause loss when the environment is favorable. However, aboveground symptoms of plants that are overwatered are similar to symptoms of root rot. Excess water can damage roots, causing tan to brown, water‑soaked symptoms on roots even if no pathogen is present.
Plant spinach in well draining soils. Prepare seed beds so that even, rapid germination is enhanced. Carefully manage the irrigation schedule to prevent flooding and saturated soil conditions. Plant seed that is treated with fungicides and fumigate the beds. Preplant application of mefenoxam will only control damping-off caused by Pythium. Avoid planting consecutive spinach crops and practice good crop rotation.
Always remember the disease triangle, the necessity of a susceptible host, the favorable environment, and virulent pathogen. To create unfavorable environment avoid overwatering, do light but frequent irrigation to avoid standing water in the field, schedule watering in the morning or earlier part of the day. Addition of soil amendments to increase microbial activity can be helpful.
Vol. 12, Issue 4, Published 2/22/2021
Keeping up to date with the latest developments in automated weeding machines is challenging. It’s a very fast-moving space with significant private and public investment. At the “Advances in Weed Control Technologies” breakout session at the 2021 Southwest Ag Summit, university experts and cutting-edge innovators will provide updates on the latest developments in automated weeding, autonomous ag robots and non-chemical weed control. The first presenter will be Tony Koselka, COO and Vice President of Engineering, Vision Robotics Corp. Tony will be giving a history on the evolution of automated thinning/weeding technologies and real-world examples of how vision systems and artificial intelligence (AI) is being used with automated weeding machines today. Following Tony will be Paul Nagel, Chief Revenue Officer, Stout Industrial Technology, Inc. Paul will be discussing AI technologies available today, their capabilities, and where the technology is headed. Jaime Eltit, Head of Commercial Farming Operations, FarmWise, Inc. will be also be discussing AI technology and how machine learning is used for robotic in-row weed control. Additionally, he will be presenting information on the latest developments in autonomous weeding robots and their application in Arizona vegetable production systems. Finally, Dr. Steve Fennimore, Weed Scientist, UC Davis will be presenting information on a novel technique for using steam heat to control sclerotinia lettuce drop, Fusarium wilt of lettuce and in-row weeds in vegetable crops.
The session will be held TOMMOROW Thursday, February 25th from 1:30-3:30. If you are unable to attend the live session, recordings of the presentations will be available on March 2 and March 3. For those interested in CEU’s, the session offers 2 AZ/CA PCA and CCA credits. One last thing, you must be registered for the 2021 Southwest Ag Summit in order to attend the session. To register or for more information about the Southwest Ag Summit, visit https://yumafreshveg.com/southwest-ag-summit/. Hope to see you there for what promises to be an enlightening and informative session.
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://188.8.131.52:460
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.