Task 2 Butte County Site

This report summarizes our progress as we approach the end of the third year of the project. The Butte County site is an orchard of 49 acres and contains four different treatment blocks plus an untreated check of ½ acre added in 2001. The entire orchard, all treatments, was treated with fungicide on every other row and weed control was the same for all treatments. The PMA II block is a “typical” soft treatment with Bacillus thuringiensis used for lepidopteran control, the OP Dorm block is treated with Diazinon plus oil during dormancy, and the OP Dorm/HS block is treated with Diazinon plus oil during hullsplit as well as during dormancy, which is a typical grower standard practice. The PMA I block is this particular growers standard practice which did not include any additional sprays in the 2001 season, so can be considered the same as the untreated check. Treatment details are as follows:

PMA II, 12 acres (This program utilizes Bt in lieu of traditional in-season sprays):

In addition, weed control was the same in all treatment blocks. The weed control consisted of four sprays with mowing in between as needed. The applications were as follows:

· (1-22-2001) Strips only treated with Roundup @ 3 pints/acre plus Goal @ 6 ounces/acre.

Mummy counts averaged 0.8 mummies per tree across all treatments. This falls below the established UC threshold of less than two mummies per tree.

This trial is monitored for PTB, NOW, web spinning mites, SJS adult males, and SJS parasitoids (Encarsia and Aphytis) from late winter through October. In each treatment pheromone traps were placed in the center of the block and monitored weekly for PTB, SJS, and NOW. Lures were changed as recommended by the manufacturer. Weekly trap counts were shared with growers, Farm Advisors, and PCA’s. Degree-days for each of these pests were calculated to determine biofixes and to provide treatment timing for those in areas where needed. Beginning in July, plots were monitored weekly for mites using the presence / absence sampling technique. Ants were also monitored and identified just before harvest using the hot dog baiting method.

SJS pheromone traps were placed in the orchard on February 26 and checked weekly for the presence of male scales. The SJS traps were also checked for parasites of the scale, Encarsia perniciosi and Aphytis species. The first scales were found in the traps March 14 and populations grew until April 11. After this date, the male scale reappeared sporadically in low numbers on May 16^th, June 21^st, August 9^th, and Sept. 10^th as can be seen in Figure 2.1. Parasites were also detected on the traps beginning March 14th and were most always present when the scales were caught on the traps, Figure 2.2. The OP Dorm block had the highest number of scale but it also had the highest number of parasites. The PMA I block had the fewest parasites with the number of Encarsia being only slightly more than double that of the SJS.

PTB pheromone traps were hung March 14 and checked twice a week to establish the first biofix. Biofix for the overwintering generation of PTB was established on April 4. By comparing trap catches and degree-days, the PTB also had biofixes on May 23 and July 6, as shown in Figure 2.3. The upper portion of the canopy was inspected for shoot strikes at the beginning of PTB generations. Five trees per treatment block were examined. Shoots with damage were clipped with pole pruners and split down the center to verify presence and identification of larvae.

The NOW egg traps were filled with ground almond bait and also placed in the orchard on March 14. The first NOW egg was detected on April 11. Eggs were cleaned off the trap whenever they were found in order to determine the weekly number of eggs. After that, there were no more NOW eggs found until the beginning of June. After the June peak, egg-laying was sporadic until the end of August when number started to increase dramatically. Cumulative trap catches through October 18, 2001 for PTB, SJS males, Encarsia, Aphytis and NOW eggs for the four treatments are listed below in Table 2.1. It is worth noting that all the treatments show similar numbers of PTB, and, to a certain extent, SJS, whether zero, one or two sprays of organophosphates were used.

	Table 2.1 Cumulative number of arthropods per trap through October 18, 2001.
	PTB	S.J. Scale	Encarsia	Aphytis	NOW
PMA I	4380	1542	3685	70	179
PMA II	4070	1215	6420	70	206
OP Dorm	3578	2030	12355	50	95
OP Dorm/HS	3247	1695	10595	90	43
Check	4265	512	11338	65	92

Beginning in July, mites were monitored weekly using the presence / absence sampling method. Differentiation between two-spotted mites and red mites were not recorded. When using the presence / absence method, leaves are examined for the presence of web spinning mites. If a leaf has one or more mites or mite eggs, it is rated as a (+). If no mites or eggs are present, then it is given a (–) rating. Mite predators and other beneficial insects are also noted. If mite predators are not present, a treatment threshold is reached if approximately 1/3 of examined leaves have mites or eggs. If predators are present, then the treatment threshold is increased to approximately 50% or more of sampled leaves with mites or eggs.

In this trial, fifteen leaves from five trees in each block (75 leaves per block) were examined for mites. At the start of mite sampling, trees in possible hot spots were monitored, and as the populations increased, trees were chosen more randomly. The two blocks not treated with organophosphates had higher numbers of web spinning mites; they also had greater numbers of predatory mites and beneficials, mostly six-spotted thrips as shown in Table 2.2. The high number of mites in the PMA II block is probably due in part to the old, partially removed almond orchard directly to the north. The remaining trees in this orchard seemed to be very old and not in the best condition. No treatment was applied to control mites.

	Table 2.2 Percent of Leaves with Mites
	Web spinning Mites	Predators/Beneficials
PMA I	42	6
PMA II	113	7
OP Dorm	3	1
OP Dorm/HS	3	1

Ants were monitored in the orchard in August to determine whether a treatment was necessary. Baited ant traps were placed in all treatment blocks. The ant species at each bait station were identified because not all species are damaging to almonds. We found Southern Fire ants in the PMA block and pavement ants in all the other treatments. We made no attempt to quantify the ant populations. No treatment was applied to control ants, and damage at harvest was very low.

European fruit lecanium, Lecanium corni, populations have been building in this orchard. The scale was not detected in the first year of the project, but a population was first detected during the dormant spur sample inspection at the beginning of the second year. European fruit lecanium (EFL) was on 8% of the dormant spurs in the PMA I and in 15% of the spurs in the PMA II soft treatments. Populations were not detected in the two treatments receiving a dormant spray, the organophosphate dormant treatment and the organophosphate dormant and hullsplit treatment. No monitoring protocol exists but a satellite project studying in-season oil sprays for the control of EFL was conducted in Butte County with treatments as follows: An untreated check, and an oil spray at two different dates, treated during summer of 2000. Ten spurs were collected from each of five trees on Jan. 31, 2001, and the number of live scale on each was counted on Feb. 9, 2001. Trees were inspected again this spring, all treatments had good control of scale, and naturally occurring parasites had provided additional control.

Another type of monitoring, dormant spur sampling, is conducted before the growing season begins, most recently on December 8, 2000. Spurs were taken from each treatment block and inspected for mites, SJS, PTB, and EFL. Counts were tabulated and compared to the two previous years of the PMA project to determine if levels are increasing or decreasing. As shown in Table 2.3, there is no increase in mites or SJS in the PMA treatments and there are more SJS parasites.

At harvest, 100 almonds were randomly collected from each of 5 trees in each treatment block for a total of 500 per treatment. Nuts were inspected for damage, and the damaging insect identified. Percent damage to each treatment block was calculated. This year, there were very low damage levels from all insect pests. The two PMA blocks reached 1% damage from ants. Damage from all other insect pests was 0.6% or less, Figure 2.4.

Those costs that are the same in all treatments are not compared in Table 2.4 (fungicide sprays and weed control). As mentioned above, the PMA I, the grower standard, does not appear in the table because there were no insecticide sprays. Product costs are taken from the UC IPM website, http://www.ipm.ucdavis.edu/ and would be similar for growers in the area.

We had another successful season with the Butte County Almond Pest Management Alliance. Our spring meeting was well attended and interest in adopting reduced risk practices remains in the forefront for growers. We were able to monitor using the same techniques as the first year, thus helping to ensure that the effects of reduced risk practices are being documented. The key to successful reduced risk practices is intensive monitoring. We will continue to monitor to follow insect populations and to ensure that the potential for economic damage is minimized.

The Almond Pest Management Alliance has been active for three years in California. Interest in reduced risk farming practices has increased as the economic viability of the methods has been demonstrated. The PMA has been beneficial for growers, industry, and the environmental and regulatory community.

The Butte County Almond PMA has been quite successful in showing that there is no more pest damage in the PMA blocks which had one or zero pesticide applications, than there is in the treatments with two sprays. Also, the PMA II cost the grower almost three times less in pesticide costs per acre.

	Date	PMA I	PMA II	OP Dorm.	OP Dorm/HS
Mite Eggs	12/7/1998	68	69	54	53
	12/3/1999	17	18	8	8
	12/8/2000	4	2	3	7
Live SJS	Date
	12/7/1998	5	2	0	6
	12/3/1999	15	11	3	3
	12/8/2000	5	1	1	2
PTB	Date
	12/7/1998	0	0	0	0
	12/3/1999	0	0	0	0
	12/8/2000	0	0	0	0
SJS parasites	Date
	12/7/1998	0	0	0	0
	12/3/1999	5	6	0	1
	12/8/2000	2	1	0	0
EFL	Date
	12/7/1998	N/A	N/A	N/A	N/A
	12/3/1999	8	15	0	0
	12/8/1999	10	0	0	0

Block	Date	Product	Product cost/acre	Application cost/acre	Total cost/acre
PMA II	Mar 22	Dipel	$ 13.75	$ 18.00	$ 31.75

OP Dorm	Jan 20	Diazinon	$ 18.60
		Oil	$ 11.80	$ 18.00	$ 48.40

OP Dorm/HS	Jan 20	Diazinon	$ 18.60
		Oil	$ 11.80	$ 18.00
	July 15	Diazinon	$ 18.60	$ 18.00	$ 85.00