David Doll1 CommentApril 1, 2016Weeds

Planning for your summer tree nut weed control

Written by: Kurt Hembree, UCCE Farm Advisor, Fresno County Winter weeds were abundant this year, thanks to the high amount of rainfall we had. Hopefully you found time between storms and were able to get into your orchards and treat for weeds. Given moist soil conditions and warming temperatures close at hand, summer weed growth is also expected to be high. So, are you ready to go with your summer weed control program? Hopefully you already know what weeds you’ll be up against. If not, look to see if there are new ones emerging in recently-watered orchards or after the last rainfall. Note specific weeds so herbicide(s) can be selected accordingly. When it comes to herbicide selection, make sure you’re using products that are effective against your specific weeds, which often vary from field to field. Also, select herbicides and rates that are appropriate for the soil type; lower rates of preemergent products are often needed on sandier soils than heavier soils. Consider using sequential treatments where appropriate if rainfall occurs in April, which can help extend control through summer. Remember to add postemergent products to the tank if weeds are already up and growing when you treat. If glyphosate-resistant horseweed, hairy fleabane, junglerice, or ryegrass are present, and you still want to use Roundup or a similar material, be sure to add another burn-down material that is effective on those weeds. Combining Treevix or Rely 280, Lifeline, or similar product with Roundup has worked well on these and a wide variety of weeds. Be sure to treat when the weeds are small for optimum control. Don’t wait to spray when weeds are large, droughty, or dense, or herbicide coverage and performance may suffer. Use spray tips, a spray volume, and spray pressure that adequately wets the weeds, while minimizes

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Brent Holtz0 commentsJanuary 27, 2014Weeds

Dormant Weed Control in Tree Nut Crops 2014

by Mick Canevari, Brent Holtz, and Brad Hanson Current dry weather has preempted most normal winter weed germination and growth while prolonged periods of dry soil has caused some early weeds to desiccate and die.  In most tree and vine herbicide trials conducted so far this winter–the untreated controls look similar to herbicide treatments, very clean and without weeds.  What to do at this point poses some interesting questions.  Will it rain? Most of us are worrying more about irrigating our almond trees this summer than controlling weeds right now. If you have some weed growth that germinated with rain our one December rain, or with fall and winter irrigations, you may want to apply a post-emergent herbicide now in order to prevent hard to kill weeds from becoming established.  The warm weather could allow these weeds to establish and become more difficult to control, impacting the success of later herbicide applications by increasing trash on the berm and reducing coverage. 

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Brent Holtz2 CommentsJanuary 9, 2013Weeds

Dormant Weed Control in Tree Nut Crops 2012-2013

 Written by Mick Canevari and Brent Holtz, UCCE San Joaquin. Weeds have a tremendous capacity to spread within an orchard.  The first line of defense is  identifying the weeds you need to control, and selecting the best herbicides or cultural practices to control those weeds.  If you use the same herbicide(s) each year, a shift to tolerant weed species will ultimately take over and a loss of herbicide effectiveness will occur.  Alternating products with different modes of action at least every couple years will improve results and insure herbicides long term viability.  The UCIPM web site has charts that show which weeds are controlled by what herbicides, and an excellent weed photo gallery that includes many weed species commonly found in California for easy identification and reference http://www.ipm.ucdavis.edu/.      

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David Doll1 CommentJune 21, 2011Weeds

Glyphosate resistant weed control

Hairy Fleabane (Conyza bonariensis)  After the meeting last week, there were quite a few growers staying after to talk with Brad Hanson (UC Davis/AES Weed Specialist) about glyphosate resistant weeds, especially fleabane.Here are a few of their questions with answers:How do I control these weeds that are missed by glyphosate?Post-emergent materials including Rely (Glufosinate), 2-4,D, and Treevix (Saflufenacil) work well on glyphosate resistant fleabane. These tend to work a lot better on small plants but not so well on large established plants that are flowering. Paraquat works pretty well usually but there are some populations of fleabane that are resistant to paraquat in the San Joaquin Valley. Growers with serious infestations should consider making a pre-emergent herbicide application this coming winter. These residual type herbicides control emerging seedlings, killing the weed before it becomes established. Depending upon your requirements for ground water protection, consider a winter application of rimsulfuron (Matrix), simazine (Princep), indazaflam (Alion), norflurazon (Solicam), or penoxsulam and oxyfluorfen (Pindar GT). Kurt Hembree’s (Farm Advisor, Fresno County) weed susceptibility charts provide more information on controlling these weeds. There seems to be major growth flushes of fleabane, is this correct?Fleabane has two major flushes – on in late fall and another in early spring. I’d estimate that 40% emerge in the fall, 40% in the spring, and the other 20% is scattered throughout the year. What about glyphosate resistant grasses – in particular ryegrass?Post-emergent options include sethoxydim (Poast), clethodim (Select Max), and glufosinate (Rely). Pre-emergents include eptc (Eptam), napropomide (Devrinol), oryzalin (Surflan), pendimethilin (Prowl H2O). More information can be found on Kurt Hembree’s weed charts for almonds. What else should we consider when attempting to manage this weed?Treat weeds before they go to seed! This helps reduce the population within the orchard.Rotate your herbicide post-emergent chemistries and consider rotating in

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