Monday, October 31, 2011

Almond Nut Quality Earns High Marks for the 2011 Season

Editor’s note: We welcome again our guest blogger UC IPM entomologist Walt Bentley, whose specialty includes managing pests in almonds.

The final almond harvest samples are being evaluated and most of you have already gotten the quality grades from your processor. Based on what laboratory assistant Alex Newton and I have found, nut quality was excellent. As might be expected, navel orangeworm (NOW) was the most common problem followed by shriveled nutmeats. There was no plant bug or ant damage and very minor peach twig borer damage. 

Table 1 below presents the infestation summary for the orchards in the San Joaquin  Sustainable Farming Project, which is directed by the Sustainable Cotton Project.

UC IPM photo by Jack Kelly Clark
Not all samples have been evaluated. Nut infestation ranged from zero to 4.8 percent.  Interestingly, the variety with the greatest damage was a Butte (hard shell) orchard. It is the orchard where our greatest navel orangeworm egg counts were found and the mummy load going into the summer was high.

Overall the infestation levels are very low. You can see from the harvests sample data that there were numerous locations where we found no infestation. Be sure to compare these results with what you get from your processor. We are still in the process of cracking almonds so, if you don’t see your orchard code in the table it means it has not been evaluated yet.  This information will be available for the fall SJSFP almond meeting, which is scheduled for November 29. A field day announcement will be mailed to you.

Figure 1 presents the pooled egg count information from all 13 almond farmers in the project. This information comes from the trapping data in the egg counts. The egg laying is not the same as the harvest sample.

This year almond development was quite late and early harvest was not really possible. We didn’t see the initiation of hull split (Nonpareil - NP) until July 20 and 100 percent NP hull spit until August 3.  NOW deposition, although later than normal, was not as affected after May. Consequently, most of the Nonpareil crop avoided infestation in July, but was completely exposed to moths in late August.

Compare your harvest date to the graph showing the development of the third period of egg laying beginning on August 10. This time frame is important because the new crop is not susceptible to NOW until the hulls split.  Once 100 percent hull split occurs the new crop can be attacked.  When moths are abundant and hull split has completed, infestation results. 

Finally, I have included a graph from work done by Dr. Dick Rice, University of California, Davis emeritus, that compares the dynamics of NOW based on either male moth capture, black light capture of males and females, and eggs found on egg traps.  Figure 2 presents this information. I interpret this to show that the egg traps are very effective in determining the dynamics of moth activity, particularly late in the season.  It gives us confidence in the information gained from egg traps.

UC IPM photo by Jack Kelly Clark
After studying the cause of your rejects, make a mental note to count mummies left after harvest in your orchard. This will be done after the leaves are gone, but it is important.  Unharvested mummies left in the orchard are the single best indicator of navel orangeworm problems to come.  Only two trees counted per acre gives a good estimate of potential problems.  Problems result when the orchard averages two mummies per tree.  Remember it is a pair of deuces, two trees per acre counted and two nuts per tree.

Walt Bentley is a long-time entomologist with the University of California Statewide Integrated Pest Management program at the Kearney Ag Center in Parlier.

Annual Cotton Tour Nears: The deadline nears to sign up for our annual Cotton Tour on Tuesday, November 8. The free day-long tour offers participants have the opportunity to meet growers, visit a gin and even pick some cotton. Buses will leave the Best Western Apricot Inn – Interstate 5 and West Panoche Road about 23 miles southwest of Firebaugh – at 8:30 a.m. and return about 4 p.m.  Spread the word to anyone you think is interested in joining us. Registration is required. Sign up at http://www.surveymonkey.com/s/RQG9P3G


Table 1.  SJ Sustainable Farming Project: almond crack out, 2011 based on 500 nut sample.

Grower ID
Variety
Harvest date
% NOW
% PTB
% Total
30
NonPareil
24 Aug
0.0
0.0
0.0
14
Butte
31 Aug
4.6
0.2.
4.8
11
Butte
1 Sep
0.0
0.0
0.0
12
NonPareil
12 Sep
2.2
0.0
2.2
12
Fritz
26 Sep
0.0
0.0
0.0
0
NonPareil
12 Sep
2.6
0.0
2.6
15
NonPareil
15 Sep
0.2
0.0
0.2
29
Butte
---
0.0
0.0
0.0
29
Padre
---
0.2
0.0
0.2
13
Monterey
13 Sep
0.4
0.0
0.4
16
Padre
23 Sep
0.0
0.0
0.0





Fig. 1. NOW egg trap oviposition, 13 Orchards West Side  
Fresno and  Madera counties, Sept. 28, 2011.



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