Hull split spray(s) for pollinators

Nonpareil harvest has been going for more than a week in the south Sacramento Valley. The third generation of navel orange worm (NOW) eggs are beginning to appear on egg traps in the region. As the Nonpareil nuts hit the ground, NOW female moths will find other places such as pollinator variety nuts to lay their eggs. So, pollinator nuts, especially in varieties like Monterey, can be damaged by NOW once hull split begins in that variety. In areas with high NOW populations, it may be worth considering spraying one or more pollinator varieties when hull split begins to reduce worm damage (click here to see an earlier post on hull split spray timing).      

 Spray timing for pollinators depends many factors including timing of NOW egg laying, Nonpariel harvest timing, and material choice. The county ag commissioner’s office tells me that, for purposes of determining spray timing based on PHI, harvest begins when the crop leaves the tree and ends – for that variety — when that crop leaves the orchard. If a pollinator variety is showing hull split before the Nonpareil are shaken, NOW are laying eggs, and the decision to protect the pollinator nuts is made, a spray should go on before the Nonpareil nuts are harvested – at the legal PHI – to give the best possible worm damage reduction. Previous spray history (Were the Nonpareils sprayed? When was that? What was the material?) will influence the spray timing as well. 

 Almond growers have a variety of pesticides available to reduce NOW damage and those materials have a wide range in PHI (see table below). Short PHI pesticides generally have shorter residual in the field, but those materials may have a fit in NOW management in pollinators, especially when working around Nonpareil harvest. Short residual materials can provide good NOW control, but you have to spray more than once. For example, Dr. Frank Zalom (UC Davis Department of Entomology) found that B.t., sprayed once a week during hull split, performed as well as Guthion (sprayed once) for NOW damage reduction in a field trial with Joe Connell, UC Farm Advisor in Butte County, several years ago. 

 Finally, please consider this post a heads up, not a how-to. Consult with your PCA on pest development, spray timing and material(s). Carefully read the label before any spray application. Use slow sprayer speeds (2 MPH) at hull split to allow the best possible coverage.

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A partial list of pesticides registered in almonds for control of navel orange worm and the PHI for almonds and for those materials. 

Material
Preharvest interval (PHI) in days
Reentry interval (REI) in hours
B.t. (Dipel, Javelin, etc.)
0
4
Delegate
1
4
Entrust (organic)
1
4
Brigade
7
12
Altacor
10
4
Belt
14
12
Intrepid
14
4
Proclaim
14
12
Lorsban Advanced
14
24
Warrior II
14
24
Asana
21
12

To see the impact of these and other pesticides on beneficial insects, click HERE.  .

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