Performance of Alion and Matrix combinations in 2013 trials

Repost from UCWeedScience blog One of the major research and extension areas in my program is weed control efficacy in orchards and vineyards.  During the 2012-13 growing season, we conducted about 50 herbicide efficacy trials in commercial orchards or research station sites.  Today I thought I’d share some data from 2012-13 orchard weed control efficacy experiments comparing various tank mixtures and sequential applications of Matrix (rimsulfuron) and Alion (indaziflam).  This work was primarily funded by the Almond Board of California, Bayer CropSciences, and DuPont.

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Herbicide Drift or Fungal Disease?

Figure 1: What caused this damage: Herbicide drift or fungal disease? Leaf samples often appear on my desk with notes asking to identify the problem. More often than not, symptoms appear shothole-ish in nature, and growers are questioning their fungicide program (Figure 1). These symptoms, however, also appear from drifting herbicides. How can one tell the difference between three common herbicides and the fungal disease shot hole? Answer: look for fungal fruiting bodies. Shot hole infected leaves can be determined by the black fruiting body that is centrally located in the lesion on the top side of the leaf (Figure 2). Figure 2: Shot Hole affectedalmond leaf. Note the blackfruiting body in the centerof the lesions.  What about telling the difference between the three herbicides? This one is a little bit harder, but it comes down to the coloring of the leaf tissue surrounding the lesion. Kurt Hembree, Weed Management Farm Advisor in Fresno County and Brad Hanson, UC Weed Specialist, have noted the following:  lesions caused by paraquat are localized, tan in color, and remain attached (figure 3). Carfentrazone (Shark) lesions have halos that lack color (figure 4). Oxfluorfen (Goal) lesions tend to have a defined halo, sometimes purplish and/or yellow in color (figure 5).  Both of these herbicides will cause lesions to fall from the leaf. Figure 3: Shot Hole like damage caused by  Gramoxone (Paraquat). Note that the lesions do not fall from the leaf To help with the diagnosis, observe the location of the damage. Is it over the whole tree, or just lower few branches? Is it just on the outer rows? Is it across both varieties? What is the history of herbicide use? Herbicide damage tends to be found on the lower portion of the tree, with damage on all varieties within the orchard. Drift damage also tends to

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