Subtropical Fruit Crops Research & Education
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Subtropical Fruit Crops Research & Education

Posts Tagged: weed control

Into the Weeds

 

Management of Weeds in Citrus Orchards

A One Hour Webinar

June 19, 2019 from 3-4pm)

Dr. Travis Bean, assistant weed science specialist in UCCE, will discuss the importance of weed management in citrus, tree age and variety considerations, scouting and weed identification, cultural and mechanical practices, and pre- and post-emergence herbicides. One DPR CE unit (other) and one CCA CE unit (IPM) are pending.

Register in advance for the webinar by clicking on the event link above.

And there are more coming:

https://ucanr.edu/sites/ucexpertstalk/

 

weeds
weeds

Posted on Monday, June 3, 2019 at 6:29 AM
Tags: citrus (328), herbicides (18), weed control (8), weeds (32)

You See It Here, You See It There - That Elusive Hairy Fleabane Everywhere

It really has gotten out of hand - Hairy Fleabane and Horseweed which are both Conyza weed species that have run rampant this year because of the extra rain.  It's also because they have become resistant to glyphosate herbicide. The problem has shown up all over the US and other parts of the world.  Gradually as resistance has grown and their resistant fairy seeds have floated wherever the winds go, the weed is having a field day everywhere in your backyard, in your orchard, in the sidewalk.  It's not just abandoned areas, but in actively managed areas where Cal Trans is doing its best.

Citrus growers who have not used preemergents in years or never used them have turned to various cocktails to knock it out.

A good description of the biology and care of Conyza can be found at:

https://anrcatalog.ucanr.edu/pdf/8314.pdf

And we along with others have written about this problem in the past - 

//ucanr.edu/blogs/topics/index.cfm tagname=Conyza , 

//ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=10648 , 

//ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=20061

 

But this year has been exceptional in the ubiquity of this plant. Something more than glyphosate is called for at this point. Glufosinate is a postemergent herbicide somewhat similar to glyphosate in name only and more expensive.  It is a broadspectrum herbicide that is effective with thorough coverage on younger stages of conyza and other weeds.  It will take some learning to get the best effect out of it.  Citrus growers have been able to use it for several years now and have enjoyed its effectiveness. We are currently working on an IR-4 registration (http://ir4.rutgers.edu/) for avocados. It is currently not registered for use in avocado.

Mature avocados are pretty good about controlling any weeds in their own orchards through ground shading and self mulching, but conyza has become a problem in young orchards.  And this new herbicide could help.

 

 

Posted on Friday, August 18, 2017 at 4:51 AM
Tags: avocado (283), citrus (328), grapefruit (27), herbicide resistance (2), lemon (99), mandarin (68), orange (69), roundup (2), weed control (8), weeds (32)

What Hath the Rain Wrought in the Avocado Foothills

 Title: Area Livestock and Natural Resources Advisor
Specialty: Rangeland Ecology and Management, Rangeland Conservation, Grazing Management, Conservation of Biological Diversity, Watershed Protection and Management.
County: San Benito County
Address:
Cooperative Extension San Benito County
3228 Southside Road
Hollister, CA 95023
Phone: 831-637-5346 x14
Email: drorao@ucanr.edu

Do you have yellow starthistle, Italian thistle, Himalaya blackberry, white top, or other common Central Coast rangeland weeds on your ranch? If so, you may be wondering which herbicides are most effective, how much they cost, what is required to purchase and spray a particular herbicide, when to spray, whether the herbicide affects grasses or clovers, and if the herbicide is safe for your livestock and pets. Many Central Coast rangeland landowners have been asking these same questions. So, I compiled this information in two tables. Table 1 shows some of our common rangeland weeds and different herbicide treatment options. Table 2 lists six of the most commonly used rangeland herbicides, and answers questions about cost, when to spray, purchasing requirements, affected plants, and grazing/pet restrictions. All of this information is already available from a variety of sources, but I have put it together in two easy to use reference tables. The tables are self-explanatory for the most part, but the information below may clarify a few things.

Integrated Pest Management (IPM)

IPM is a weed management approach that uses multiple control methods. Control methods could include mechanical control, manual control, grazing, seeding, herbicide, etc. The most effective options will depend on the particular species you are trying to control. This blog post focuses on herbicide because I am often asked about chemical treatment options. However, your weed control efforts will likely be most successful if you use a variety of methods.

Operator ID's, Restricted Materials Permits, & Private Applicator Certificates

Most of the herbicides in Table 2 are general use pesticides, meaning that you only need an operator ID to purchase and use them (Carbonaro, pers. comm.). Operator ID's are free and can be obtained from your County Agricultural Commissioner's office. No test is required. But, you'll need to show a property map in order to get your operator ID.

One herbicide in Table 2, 2, 4-D, is a California state restricted pesticide when applied on rangelands. Before you can purchase or spray California state restricted pesticides, two things are required: a Private or Commercial Applicator Certificate and a restricted materials permit. You can get a Private Applicator Certificate from your County Ag Commissioner's office. This requires taking a free test. The test is based on Pesticide Safety: A Reference Manual for Private Applicators, 2nd Ed., published by the University of California. This book can be purchased from most County Ag Commissioner or UC Cooperative Extension offices or online at: http://anrcatalog.ucanr.edu/Details.aspx?itemNo=3383. Once you have your Private Applicator Certificate you'll be able to obtain a restricted materials permit, again from your County Ag Commissioner's office. Alternatively, you can hire a licensed pest control business to purchase and spray California state restricted pesticides.

Read Labels, Follow Federal, State & Local Regulations, and Report Pesticide Use to Your County Ag Department

Although Table 2 includes information from the herbicide labels, it is not a substitute for reading the entire herbicide label before you spray (Carbonaro, pers. comm.). Always read the label before using any of these herbicides. In California, in addition to following the label, applicators will also need to follow federal, state, and local regulations. And, remember that you should submit a pesticide use report to your County Agricultural Commissioner's office for all pesticides used on rangelands.

For additional information about weeds and how to manage them, check out this website: http://wric.ucdavis.edu. The Invasive Thistles of Bay Area Counties & Herbicides for Controlling Thistles Handout compiled by Guy Kyser, UC Cooperative Extension Specialist in Weed Science at UC Davis is a great resource and is attached at the bottom of this blog post.

References

Carbonaro, D. 2017. Personal communication, 4/16/2017. Carbonaro is a Senior Biologist/Inspector with the San Benito County Agricultural Commissioner's Office.

DiTomaso, J.M. G.B. Kyser et al. 2013.  Weed Control in Natural Areas in the Western United States.  WRIC, UC.

Kyser, G. Unpublished. Invasive Thistles of Bay Area & Herbicides for Controlling Thistles.

 

Table 1. Common Central Coast Rangeland Weeds

PlantSpecies

Herbicides Options Approved for useon CaliforniaRangelands

Rangeland Herbicides Known to beEffective

 

Bullthistle

(Cirsium vulgare)

2, 4-D (Severalnames) Aminopyralid(Milestone) Clopyralid(Transline) Dicamba (Banvel,Clarity)

Triclopyr (Garlon 3A/Garlon 4Ultra)Chlorsulfuron(Telar)

Imazapyr (Arsenal,Polaris)

Milestone, Transline, Capstone (=Milestone + Garlon),Garlon, Roundup (Kyser,unpublished)

 

2,4-D is often used because it is inexpensive. However, itis not as effective as otherherbicides.

Bull thistle weed report:

 http://wric.ucdavis.edu/information/natural%20areas/wr_C/Cirsium_vulgare.pdf

Cocklebur (commonand spiny cocklebur) (Xanthium strumarium) (Xanthium spinosum)

2, 4-D (Severalnames) Aminopyralid(Milestone) Clopyralid(Transline) Dicamba (Banvel,Clarity) Fluroxypyr (VistaXRT)

Triclopyr (Garlon 4 Ultra, RemedyUltra)Glyphosate (Roundup, Accord XRT II,and others)

Imazapyr (Arsenal,Polaris) Sulfosulfuron(Outrider)

Aminopyralid(Milestone) Clopyralid(Transline)

Cocklebur weed report:

 http://wric.ucdavis.edu/information/natural%20areas/wr_X/Xanthium_spinosum-strumarium.pdf

Fiddleneck (Menziesandcoastfiddleneck) (Amsinckiamenziesii)(Amsinckia menziesiivar. intermedia)

Aminopyralid(Milestone)

Glyphosate (Roundup, Accord XRT II,and others)

Chlorsulfuron(Telar)Imazapyr (Arsenal,Polaris) Sulfosulfuron(Outrider)Hexazinone (VelparDF)

Aminopyralid(Milestone) Chlorsulfuron(Telar)

Fiddleneck weedreport:

http://wric.ucdavis.edu/information/natural%20areas/wr_A/Amsinckia.pdf

 

Foxtail (Mediterraneanand harebarley)

(Hordeum marinumssp.gussonianum) (Hordeum murinumssp.leporinum)

Glyphosate (Roundup, Accord XRT II,and others)

Imazapyr (Arsenal,Polaris) Rimsulfuron(Matrix)

Sulfometuron + chlorsulfuron(LandmarkXP)

Sulfosulfuron(Outrider)Hexazinone (VelparL)

Glyphosate (Roundup, Accord XRT II, and others) iseffective, but is nonselective, so will kill most other plants as well.If glyphosate is to be used, reseed to reduce bare groundand encroachment of other weedspecies.

 

Rimsulfuron (Matrix) will likely control control foxtail,based on limiteddata.

Foxtail weedreport:

http://wric.ucdavis.edu/information/natural%20areas/wr_H/Hordeum_marinum-murinum.pdf

Frenchbroom

(Genista monspessulana)

Triclopyr (Garlon 3A, Garlon 4Ultra,PathfinderII)

Aminopyralid + triclopyr(Capstone) Triclopyr + 2,4-D(Crossbow)

Glyphosate (Roundup, Accord XRT II,and others)

Imazapyr (Arsenal,Polaris)

Triclopyr (Garlon 3A, Garlon 4 Ultra, PathfinderII)

 

Glyphosate (Roundup, Accord XRT II, and others) iseffective, but resprouts will need to be controlled. Glyphosateis nonselective, so will kill most other plants as well. Ifglyphosate is to be used, reseed to reduce bare groundand encroachment of other weedspecies.

French broom weedreport:

http://wric.ucdavis.edu/information/natural%20areas/wr_G/Genista.pdf

Goatgrass (jointed and barbgoatgrass) (Aegilops cylindrica) (Aegilops triuncialis)

Glyphosate (Roundup, Accord XRT II,and others)

Sulfometuron + chlorsulfuron(LandmarkXP)

Research is currently being conducted to identify most effective options for goatgrass.

Goatgrass weedreport:

http://wric.ucdavis.edu/information/natural%20areas/wr_A/Aegilops_cylindrica-triuncialis.pdf

 

Himalayablackberry

(Rubus armeniacus)

Dicamba (Banvel,Clarity) Fluroxypyr (VistaXRT)

Triclopyr (Garlon 3A, Garlon 4Ultra,PathfinderII)

Aminopyralid + triclopyr (Capstone) Glyphosate (Roundup/Accord XRT II,and others)

Hexazinone (VelparL) Tebuthiuron(Spike)

Triclopyr (Garlon 3A, Garlon 4 Ultra, Pathfinder II) canbe effective on smallindividuals.

 

Glyphosate (Roundup/Accord XRT II, and others) canbe effective, but may requireretreatment.

Himalaya blackberry weed report:

http://wric.ucdavis.edu/information/natural%20areas/wr_R/Rubus.pdf

Italian thistle

(Carduus pycnocephalus)

2, 4-D (Severalnames) Aminopyralid(Milestone) Aminopyralid + 2,4-D (ForefrontHL) Aminopyralid + triclopyr(Capstone) Clopyralid(Transline)

Dicamba (Banvel,Clarity) Fluroxypyr (VistaXRT)

Triclopyr (Garlon 3A, Garlon 4Ultra)Triclopyr + 2,4-D(Crossbow)

Glyphosate (Roundup, Accord XRT II,and others)

Chlorsulfuron(Telar)Imazapyr (Arsenal,Polaris) Hexazinone (VelparL)

Aminopyralid (Milestone) is highly effective on thistles.

 

Milestone, Transline, Capstone (=Milestone + Garlon),Garlon, Roundup (Kyser,unpublished)

 

2,4-D is often used because it is inexpensive. However, itis not as effective as otherherbicides.

Italian thistle weedreport:

http://wric.ucdavis.edu/information/natural%20areas/wr_C/Carduus_acanthoides-nutans-pycnocephalus-tenuiflorus.pdf

 

Medusahead (Taeniatherumcaput

-medusae)

Aminopyralid(Milestone)

Glyphosate (Roundup, Accord XRT II,and others)

Rimsulfuron(Matrix) LandmarkXP

Aminopyralid (Milestone) provided up to 90% controlof medusahead  based on research in the CentralValley.

Medusahead weedreport:

http://wric.ucdavis.edu/information/natural%20areas/wr_T/Taeniatherum.pdf

Milkthistle

(Silybum marianum)

2, 4-D (Severalnames) Aminopyralid(Milestone) Clopyralid(Transline) Dicamba (Banvel,Clarity) Chlorsulfuron(Telar)Rimsulfuron(Matrix)

Milestone, Transline, Capstone (=Milestone + Garlon),Garlon, Roundup (Kyser,unpublished)

Milk thistle weedreport:

http://wric.ucdavis.edu/information/natural%20areas/wr_S/Silybum.pdf

Purple starthistle

(Centaurea calcitrapa)

2, 4-D (Severalnames) Aminopyralid(Milestone) Clopyralid(Transline) Dicamba (Banvel,Clarity)

Glyphosate (Roundup, Accord XRT II,and others)

Hexazinone (VelparL)

Milestone, Transline, Capstone (=Milestone + Garlon),Garlon, Roundup (Kyser,unpublished)

Purple starthistleweed report:

http://wric.ucdavis.edu/information/natural%20areas/wr_C/Centaurea_calcitrapa-iberica.pdf

 

Tumbleweed(Russian thistle)

(Salsola tragus)

2, 4-D (SeveralNames) Aminocyclopyrachlor +Aminopyralid(Milestone) Dicamba (Banvel,Clarity)

Triclopyr (Garlon 3A, Garlon 4Ultra)Glyphosate (Roundup, Accord XRT II,and others)

Chlorsulfuron(Telar)Imazapyr (Arsenal,Polaris) Hexazinone (VelparL)

Research is currently being conducted to identify most effective options fortumbleweed.

Tumbleweed weedreport:

http://wric.ucdavis.edu/information/crop/natural%20areas/wr_S/Salsola_paulsenii-tragus.pdf

Whitetop/hell weed

(Cardaria draba)

2, 4-D (Severalnames) Dicamba + 2,4-D

Glyphosate (Roundup, Accord XRT II,and others

Chlorsulfuron(Telar)Imazapyr (Arsenal,Polaris)

Chlorsulfuron (Telar) is one of the best control optionsfor plants in the Cardariagenus.

 

2,4-D is often used because it is inexpensive. However, itis not as effective as otherherbicides.

Whitetop weedreport:

http://wric.ucdavis.edu/information/natural%20areas/wr_C/Cardaria_chalepensis-draba-pubescens.pdf

Yellowstarthistle

(Centaurea solstitialis)

2, 4-D (Severalnames) Aminopyralid(Milestone) Clopyralid(Transline) Dicamba (Banvel,Clarity)

Triclopyr (Garlon 3A, Garlon 4Ultra)Glyphosate (Roundup, Accord XRT II,and others)

Chlorsulfuron(Telar)Imazapyr (Arsenal,Polaris) Hexazinone (VelparL)

Aminopyralid (Milestone) is the best option to controlyellow starthistle.

 

Clopyralid (Transline) is also veryeffective.

 

Glyphosate (Roundup, Accord XRT II, and others) is thebest option in the lateseason.

Yellow starthistleweedreport:

 http://wric.ucdavis.edu/information/natural%20areas/wr_C/Centaurea_solstitialis.pdf

 

Table 2. Commonly Used Rangeland Herbicides, Including When and How to Use Them

Chemical Name/Product Name1

 

 

Price2*

Registered

for useonCalifornia rangelands3

Requirements to Purchase/Spray Herbicide3

 

Preemergent/ Postemergent1

 

 

Best time tospray4

 

 

TargetedPlants4

Triclopyr(Garlon 3A/Garlon 4Ultra,Remedy Ultra,PathfinderII)

$70/gallon

Yes

Operator ID#

Postemergent

Spray after all of theweed seed has germinated,but before the plants getbig.

Kills broadleaves, but not grasses

 

Killsclovers5

Aminopyralid(Milestone)

$300/gallon

Yes

Operator ID#

Preemergentand postemergent

January -March

Kills thistles andlegumes, and some otherbroadleaves, but notgrasses

 

Killsclovers5

Glyphosate (Roundup, Accord XRT II, and others)

$21/gallon

Yes

Operator ID#

Postemergent

Spray after all of theweed seed has germinated,but before the plants getbig.

Kills any greenvegetation. Tree leaves can be sprayed, but it will not be effectiveifsprayed on treetrunks.

 

 

Chemical Name/Product Name1

 

 

Price2*

Registered

for useonCalifornia rangelands3

Requirements to Purchase/Spray Herbicide3

 

Preemergent/ Postemergent1

 

 

Best time tospray4

 

 

TargetedPlants4

Chlorsulfuron (Telar)

$21/ounce

Yes

Operator ID#

Preemergent,

can also be usedas postemergent

Spray around the timeof the first rains, a littlebefore or a little afterthe first rains is fine.Spraybefore seedilngs getbig.

Check label for plants affected. This herbidiceisspecies specific. Although,itis generally safe on grasses1.

 

Killsclovers5

Clopyralid(Transline)

$170/gallon

Yes

Operator ID#

Postemergent

Spray after all of theweed seed has germinated,but before the plants getbig.

Kills thistles and legumes,but notgrasses

 

Killsclovers5

2, 4-D (DMA4IVM,

Weedar 64and manyothers)

2, 4-D Amine-

$13/gallon2, 4-D Ester-

$19/gallon

Yes

Restricted materialspermit and applicator certificate

Postemergent

Spray after all of theweed seed has germinated,but before the plants getbig.

Kills broadleaves, but not grasses

 

Killsclovers5

 

Triclopyr(Garlon 3A/Garlon 4Ultra,Remedy Ultra,PathfinderII)

"Grazing green forage: There are no grazing restrictions for livestock or dairy animals on treated areas...Haying (harvesting ofdried forage): Do not harvest hay for 14 days after application...Slaughter Restrictions: During the season of application, withdrawlivestock from grazing treated grass at least 3 days before slaughter...Livestock Use of Water from Treatment Area: There are no restrictionson livestock consumption of water from the treatmentarea."

Herbicide Label:https://s3-us-west-1.amazonaws.com/www.agrian.com/pdfs/Garlon_3A_Label1i.pdf

Aminopyralid(Milestone)

"Grazing and Haying Restrictions: There are no restrictions on grazing or grass hay harvest following application of Milestone atlabeledrates. Cutting hay too soon after spraying weeds will reduce weed control. Wait 14 days after herbicide application to cut grass haytoallow herbicide to work. Do not transfer grazing animals from areas treated with Milestone to areas where sensitive broadleafcrops occur without first allowing 3 days of grazing on an untreated pasture. Otherwise, urine and manure may contain enoughaminopyralidto cause injury to sensitive broadleaf plants...For applications on rangeland and permanent grass pastures (not harvested for hay)andnon-cropland areas, do not enter or allow worker entry into treated areas until sprays have dried...Grazing Poisonous Plants:Herbicideapplication may increase palatability of certain poisonous plants. Do not graze treated areas until poisonous plants are dry andnolonger palatable to livestock...Hay from grass treated with Milestone within the preceding 18-months can only be used on the farmor ranch where the product is applied unless allowed by supplemental labeling." Check label for specific restrictions on moving hay,or using hay for silage,etc.

Herbicide Label:https://s3-us-west-1.amazonaws.com/www.agrian.com/pdfs/Milestone_Label1h.pdf

Glyphosate (Roundup, Accord XRT II, and others)

"DOMESTIC ANIMALS: This product is considered to be relatively nontoxic to dogs and other domestic animals; however, ingestionof this product or large amounts of freshly sprayed vegetation may result in temporary gastrointestinal irritation (vomiting, diarrhea,colic, etc.). If such symptoms are observed, provide the animal with plenty of fluids to prevent dehydration. Call a veterinarianifsymptoms persistfor morethan24hours...Donotfeedor grazeturfgrass grownfor seedor sodproductionfor 8weeks followingapplication...If application rates total 4.5 pints per acre or less, no waiting period between treatment and feeding or livestockgrazing is required. If the rate is greater than 4.5 pints per acre, remove domestic livestock before application and wait 8 weeksafter application before grazing orharvesting."

Herbicide Label:https://s3-us-west-1.amazonaws.com/www.agrian.com/pdfs/Roundup_Custom_Label2.pdf

 

 

Chlorsulfuron (Telar)

"There are no grazing or hay harvest restrictions for any livestock, including lactating animals, with application rates up to 11/3 ounces/acre of TELAR® XP. No exclosure is required for any animals. Do not apply more than 1 1/3 ounces/acre of TELAR® XP peracreper year. No exclosure is required for anyanimals."

Herbicide Label:https://s3-us-west-1.amazonaws.com/www.agrian.com/pdfs/DuPont_Telar_XP_Herbicide_Label5a.pdf

 

Clopyralid(Transline)

"Grazing/Haying: There are no restrictions on grazing or hay harvest following application of Transline at labeled rates exceptfor exported grass hay from California, Nevada, Washington and Oregon (see instructions in the Range and Permanent GrassPasturesection)...Do not transfer livestock from treated grazing areas, or from feeding of treated hay, to sensitive broadleaf cropareaswithout first allowing 3 days of grazing on an untreated pasture (or feeding of untreated hay). If livestock are transferred withinless than 3 days of grazing untreated pasture or eating untreated hay, urine and manure may contain enough clopyralid to cause injuryto sensitive broadleaf plants...For applications to fallow cropland, rangeland, pasture, and non-crop areas, do not enter treatedareasuntil sprays have dried. For early entry to treated areas, wear eye protection, chemical-resistant gloves made of anywaterproof material, long-sleeved shirt, long pants, shoes andsocks."

Herbicide Label:https://s3-us-west-1.amazonaws.com/www.agrian.com/pdfs/Transline1v_Label.pdf

2, 4-D (DMA4IVM,

Weedar 64and manyothers)

"For grazed areas, the maximum use rate is 4.21 pints of DMA 4 IVM (2 lb of acid equivalent) per acre perapplication...Preharvest Interval: Do not apply within 7 days of cutting forage for hay... If grass is to be cut for hay, Agricultural Use Requirements for the Worker Protection Standard areapplicable."

Herbicide Label:https://s3-us-west-1.amazonaws.com/www.agrian.com/pdfs/DMA_4_IVM_Label1d.pdf

 Tables 1 $ 2 from Devii Rao, drorao@ucanr.edu

starthislte 2
starthislte 2

starthistle
starthistle

Posted on Monday, August 14, 2017 at 6:13 AM
  • Author: Devii Rao
Tags: avocado (283), fire (30), foothills (1), weed control (8), wild lands (2), wildfire (2), wildlands (3)

Orange Costs of Production

The latest cost of production study done on oranges came out recently.

http://coststudyfiles.ucdavis.edu/uploads/cs_public/19/d4/19d4f1bb-408a-443e-a759-36fd53a2948f/oranges_vs_2015.pdf

It applies to the San Joaquin parts of the Valley for sure, but many of the assumptions are true for evergreen tree crops in general.  The cost of weed control, or fertilizing are not going to be different.  Pest and disease control are going to be very different if you are a navel orange grower in Bakersfield or a cherimoya grower in Santa Barbara.  The key to these studies are the different issues/categories a grower should be addressing and the studies provide a framework for that study.  Also it gives general costs for different inputs, such as urea and glyphosate to make a comparison to what you might be paying

 

citrus weeds 2
citrus weeds 2

Posted on Saturday, November 7, 2015 at 8:06 AM
Tags: ag economics (1), avocado (283), cherimoya (14), citrus (328), dragon fruit (5), economics (4), production (9), weed control (8)

Weed Control in Subtropical Tree Crops

 

Control of weeds has always been a major economic cost in subtropical fruit production because of favorable climate that allows for weed germination and year-round growth. The use of chemical weed control has increased dramatically due to labor costs, equipment costs, product costs and availability, the shift to more narrowly spaced tree rows, and installation of low volume irrigation systems that prohibit the operation of mowing or tillage equipment under the tree canopy area (Futch 2001).

However finding herbicides that are labeled for certain subtropical crops can be a bigger challenge. UC Weed Science has updated the Subtropical Crops herbicides usage chart for California growers (Fig. 1 Attachment below). It also seems that preventive programs are most frequently overlooked as a method of weed control. Preventive programs entail the use of such practices as sanitation, spot spraying, or hand labor to prevent the source of weed infestation (seed and/or vegetative) from widespread dissemination throughout a given area. By removing the undesirable weed species prior to seed development, dissemination by wind or mechanical transport on equipment can be effectively delayed.

Weed control programs will vary from location to location within the state and can even vary within a given site based upon specific conditions such as soil type, variety, method of herbicide application, and the presence of specific weed species.

Before herbicide application, growers should survey the grove and determine the stage of growth and type of weeds for that given location. Many products do not provide control of emerged species, thus requiring the application of more than one product to provide both preemergence and postemergence protection (Futch 2001). Rotation of soil-applied herbicides should also be considered to prevent the buildup of resistant annual and perennial weeds. The resistant species may not be evident initially; however, if the same herbicide and cultural program is maintained, over time their populations may build up until they infest the entire grove and become the dominant weed species (Jordan et al 1992).

 Herbicide damage to foliage and fruit has also been noted when herbicides were applied under windy conditions or use of improper equipment allowed the materials to contact areas other than the weeds or soil. Please make sure to follow the label's direction and use caution.

Attached below is a chart listing herbicides registered for avocado, citrus, date, kiwi, fig and pomegranate.

Posted on Thursday, October 22, 2015 at 8:29 PM
Tags: avocado (283), citrus (328), Dates (2), Figs (1), Kiwis (1), pomegranate (5), subtropical tree crops (3), weed control (8), Weeds (32)

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