Task 3:

Kern County

Introduction:

The purpose of this project was to demonstrate a reduced pesticide input versus a conventional pesticide program in young almond orchards. The comparison between the two programs is found in Appendix A. It has the comparison of 1999 and 2000.

An individual site was found with two, 40-acre blocks of "hard" shell varieties (Butte, Mission and Padre) and two, 40-acre blocks of "soft" shells (Nonpareils, Sonora and Fritz). Each 40-acre block was divided into reduced input and conventional programs. This gave us two replications in both "hard" and "soft" shell varieties. The demonstration was started in November, 1998 with the planting of a cover crop and has continued until the present time.

Cover Crop:

Barley was selected as the cover crop because of the saline-alkali and poor drainage conditions of the soil. The barley was seeded in every middle on both "soft" and "hard" shell blocks at a rate of 40 lbs. per acre. This was done in November of 1998 and 1999. Also, at the same time, an insectary was established in every 11^th middle using the "Bios Insectary Mix" at a seeding rate of 10 lbs. per acre. This insectary mix will not be planted in November of 2000. The reason being that it was difficult to establish in 1998 and 1999. Furthermore, the "insectary mix" didn’t increase predator insects that controlled key pests.

The barley germinated well in 1998 due to winter rains. The result was a solid cover in the middles. In 1999, there was poor winter rains and the barley didn’t germinate well, but it did still make a good cover in the middles.

The "Bios Insectary Mix" was planted in 1998 and in 1999. Appendix B shows the composition of both mixes. The germination of both mixes was poor. There were good amounts of rain fall in 1998, but not in 1999, however, the germination was poor in both years. The clovers, rye, vetch, coriander, and celery failed to germinate in 1998 and only a few plants of toothpick weed and yarrow were present in this year. The germination was not any better in 1999. The insectary seed was planted within the wet zone of the mini-sprinkler. There, some clovers, toothpick weed, California poppy, yarrow, baby blue eyes and sweet alyssum germinated in the middles. The amount of insectary plants was not plentiful enough to create a thick cover. Nevertheless, it did provide a habitat for ladybug insects.

One of the benefits of the barley cover crop was on water infiltration rates. The water infiltration rate was greater where barley was planted than the natural vegetation in May, July, and October. The differences in the rate of infiltration can be seen in Graphs 1, 2, and 3.

Graph 1. Kern Co. Rate of infiltration (inches/hour) in barley and natural vegetation cover crops in orchard middles during May.

Graph 2. Kern Co. Rate of infiltration (inches/hour) in barley and natural vegetation cover crop orchard middles during July.

Graph 3. Kern Co. Rates of infiltration (inches/hour) in barley and natural vegetation cover crop orchard middles during October.

Pest Monitoring

Trapping for three key pests of almonds was done throughout the season. Traps were hung together on the same tree, seven trees in from the end of the row in Nonpareil and Mission varieties. Three San Jose Scale sticky traps were placed per block, six to seven feet high in the northeast quadrant of the tree on February 22, 1999. In 2000, only two sticky San Jose traps were placed per block. Traps were placed on March 24^th. In both years, the traps were monitored weekly until the end of November. Pheromone lures were replaced every four weeks. Adult San Jose Scale moths were counted, as well as the Encarsia and Aphytis adults. Double-sided sticky tapes were placed one per tree in each of the four trees surrounding the "trap tree" on April 15, 1999, and were collected and replaced every other week through November. The number of San Jose Scale crawlers per tape were then counted and recorded. Two peach twig borer traps were placed per block, six to seven feet high in the northeast quadrant of the tree on March 22, 1999.

The same number of traps, in the same location and at the same height, were placed on March 23, 2000. Adult moths were counted weekly until the end of November. Pheromone lures were replaced every eight weeks. Two navel orangeworm traps per block containing an almond meal mixture were placed six to seven feet high in the north side of the tree on March 29, 1999. In 2000, following the same procedure, navel orangeworm traps were placed March 31^st. Eggs laid on the exterior grooves of the trap were counted weekly through the end of November. Bait was replaced every eight to ten weeks.

Dormant Spray

The dormant spray of 1999 consisted of five pints of Diazinonâ and six gallons of oil in 200 gallons of water per acre. The spray date was January 4^th. This was the conventional dormant spray program. The reduced input was left unsprayed. The dormant spray program for the 2000 season was changed to the following: The conventional program consisted of three pints of Lorsban, four gallons of oil and 230 gallons of water per acre and the reduced input received six gallons of oil and 230 gallons per acre. The reason for the change in the dormant spray program in the conventional program was due to a dry and low chilling year. Common beliefs tell us that oil phytotoxicities can occur during a dry and poor chilling year. The reason the reduced input was sprayed with 6 gallons of oil was to prevent the buildup of San Jose Scale. Please note, there was no phytotoxicity due to oil in these treatments.

The dormant spray program has given us mixed results for key pests in the PMA orchard. Table 1 shows that PTB emergence was not affected by the dormant spray in 1999. Both conventional and reduced input shows similar amounts of emergence. Based on this information, one can question the value of dormant spray for the control of PTB. In the year 2000, we were unable to evaluate the dormant spray on PTB emergence. The reason, there was no hibernacula in the conventional or in the reduced input treatments.

Table 1. Kern Co. Percent of PTB emergence from samples taken at different dates from reduced input and conventional treated blocks.

Dormant sprays are also evaluated on the number of PTB shoot strikes in the spring. In the 1999 season, (Graph 4) dormant sprays had little effect in reducing the number of strikes. In fact, both dormant and non-dormant treatments show similar counts in April and same amounts in June.

Graph 4. Kern Co. The average number of strikes per tree on April 19 and June 30 in both reduced input and conventional spray programs.

Furthermore, Graph 5 shows that PTB adult population in the 1999 season was not affected by the dormant spray. Both conventional and reduced input had similar numbers through the 1999 growing season.

Graph 5. Kern Co. The average number of PTB adults per trap during the 1999 season in both reduced input and conventional spray programs.

In the 2000 season, (Graph 6) the number of shoot strikes per tree were lower than in the 1999 season. Also, the number of strikes per tree was higher early in the season and decreased at the end of the season. Furthermore, based on the number of strikes per trees from both conventional and reduced input, one can conclude that the dormant spray in 2000 didn’t decrease the strikes per tree in the PMA orchard.

Graph 6. Kern Co. The average number of strikes per tree on May 30 and June 25 in both conventional and reduced input dormant spray programs.

The adult population of PTB was lower in 2000 than in 1999. Please look at Graph 5 and Graph 7. There were distinctive peaks in early April, late May and mid-October, and generally speaking, the conventional had higher counts than the reduced input. Again, looking at Graph 4, one may conclude that the conventional dormant spray program doesn’t control PTB.

Graph 7. Kern Co. The average number of PTB adults per trap during the 2000 season in both conventional and reduced input spray programs.

The organophosphate (Diazinonâ 1999) and (Lorsbanâ 2000) reduced the ant population in the 1999 and 2000 season. Graphs 8 and 9 show a reduction in ant population in the conventional spray program in both seasons.

Graph 8. Kern Co. Average number of ants per vial on both reduced input and conventional programs from three different sampling dates.

Graph 9. Kern Co. Average number of ants per vial on three sampling dates on both conventional and reduced input dormant programs.

Winter Sanitation

Mummy removal (the elimination of last year’s nuts) or sanitation and timely early harvest can reduce navel orangeworm (NOW) between 0 and 4% in the Southern San Joaquin Valley.

In 1999, sanitation was done and evaluated in January. Five percent of the trees per row of Nonpareil, Fritz, Butte, and Mission varieties were surveyed. After walking in one or two trees, every 18^th tree was selected for a total of four trees per row; total mummies per tree were counted, including sticktights and mummies that had been cleaned out by birds.

Graph 10 shows the results of this evaluation. There were less mummies per tree in the Butte variety from the conventional than from the reduced input. However, there were more mummies in Fritz, Mission and Nonpareil varieties in the conventional than on the reduced input. Unfortunately, both reduced input and conventional programs had more mummies than is recommended in the IPM manual. The recommendation is two mummies per tree.

Graph 10. Kern Co. Average number of mummies per tree in Butte, Fritz, Mission and Nonpareil varieties from the reduced input and conventional programs.

In the 2000 winter season, sanitation was also done and evaluated in January. Approximately 2.5 percent of each variety were checked. In addition to counting the mummies remaining in the trees, samples were brought in and examined for infestation of live navel orangeworm (Graph 11). These samples were not variety specific, but represented the "in orchard" infestation of navel orangeworm. The general trend is for hard shell varieties to have more mummies (Table 2). It was noted that there were very few mummies on the ground. By returning to the orchard after dark, we found a lot of field mice. It is assumed they are feeding on the mummies that fall to the ground.

Table 2. Average number of mummies per tree from different varieties in both the conventional and reduced spray programs.

Average Number of Mummies per Tree

Graph 11. Kern Co. Navel orangeworm infestation of mummies from the four replications and from both conventional and reduced input program.

The percent of NOW infestation was acceptable. However, the percent of infestation in the conventional was higher than in the reduced input programs.

The average number of eggs of NOW for the 1999 and 2000 growing season are found in Graph 12 and Graph 13 respectively. In the 1999 season, the number of eggs per trap from the first generation is slightly higher in the reduced input than in the conventional program. However, this situation drastically changes in the second and third generation, where the number of eggs per trap is significantly higher in the conventional than in the reduced input. It appears that Successâ at 6 oz. per acre or Imidanâ at 5 1/3 lbs. per acre (applied at hull split) had no effect in reducing NOW eggs. It is possible, however, that organophosphate (dormant spray) and Imidanâ (hull split) may have affected NOW predators in the conventional blocks. In the 2000 growing season, during the first generation, the number of NOW eggs per trap were higher in the conventional program than in the reduced input program. There were no differences between these two programs during the second generation, but on the third generation, the number of NOW eggs were higher in the reduced input than in the conventional program. During the fourth generation, however, the number of eggs reversed from the reduced input to the conventional. The Imidanâ spray at 5 1/3 lbs per acre may have reduced the number of eggs per trap during the second generation in the conventional program.

Graph 12. Kern Co. Average number of NOW eggs per trap from April to October in the conventional and reduced program.

Graph 13. Kern Co. Average number of NOW eggs per trap from April to October in the conventional and reduced input program.

San Jose Scale

San Jose Scale (SJS), Quadraspidiotus perniciosus, was monitored in the Kern County Pest Management Alliance Orchard using three methods. On February 25, SJS sticky traps were baited with SJS pheromone loaded rubber septa (Tre¢ ce¢ ) to monitor male scale flight in each of the eight almond plots. Two such traps were placed approximately 1/3 the way in from each of the north and south ends of the plots. Male scale, and the two key parasitoids, Encarsia perniciosi and Aphytis spp., were counted weekly. In late March, a single limb from each of the trees at the four compass points around the tree holding the pheromone trap were wrapped with double sided sticky tape to monitor SJS crawlers. Finally, in December, 100 spurs were collected from each plot to determine infestation, scale growth stage, parasitism, and wood mortality.

Monitoring was done to detect short-term differences in scale abundance, and long-term establishment of SJS and associated parasitoids and the impact these arthropods have on wood mortality.

Graph 14 presents the dynamics of SJS male flight in both the reduced input and the conventional program. No differences in flight trends could be detected. A total of 929 dd (51° F lower and 90° F upper threshold) were accumulated from the beginning of overwintering scale flight on March 17 to the beginning of the next flight on May 22. The second flight started on May 22^nd. From May 22 to July 12 (beginning of third flight) required 1188 dd. Estimated average development time is 1050 dd. Remaining flights were not clearly discernable, but continued in early November. Although more males were trapped under the conventional program of dormant oil and organophosphate dormant spray (3720 SJS) compared to the reduced input of oil spray only (2861 SJS), these numbers were not statistically different.

Encarsia perniciosi abundance found on SJS pheromone traps was virtually identical between the two treatments. The reduced input treatment averaged 920 Encarsia per season and the conventional treatment averaged 819 Encarsia per season.

Crawler abundance for the year 2000 has not been tabulated to date. Although there does appear to be significantly more crawlers in the reduced input block, the higher numbers were found in only one replicate. In 1999, an average of 4.71 crawlers per inch of tape were found in the reduced input and 1.26 crawlers per inch of tape in the conventional.

The 1999 trends in crawler abundance will be compared to the 2000 trends. From the 1999 work, a more thorough job of dormant oil spray may be necessary to keep the apparent trend in Graph 15 from continuing.

Sampling for wood damage during December 1999 resulted in no scale damaged wood. The reduced input sampling of 240 spurs averaging three inches in length resulted in three spurs with a single black cap scale. Only one spur was infested in the conventional treatment (four scale on the one spur).

As the double sided sticky tapes and spur samples are counted, these figures may change. However, the use of a dormant oil alone in 1998 has not resulted in damaging populations of SJS in the orchard studied. We will also be evaluating parasitism in the dormant spur sampled wood to detect differences in parasitism between the two treatments.

Graph 14.Kern Co.

Graph 15. Kern Co.

Mite Management

Mites are the most difficult and most expensive pests in almonds in the Southern San Joaquin Valley. It is a pest that is predisposed by high temperatures and water stress. High temperatures of 100° F or more plus water stress in the trees can lead to an explosion of mites in the orchard. In some years, three or more miticide sprays are required to bring mites under control. If mites are not controlled, yields can decrease up to 20% the following year.

Soil monitoring was started in the 2000 season. The objective was to determine overwintering mites in the soil in both conventional and reduced input programs. There were four soil sampling dates: February 15, February 22, March 15, and March 22^nd. The soil samples were taken from the base of the trees and placed in eight ounce Styrofoam cups which were filled to the rim. Then, they were placed on a sticky card and left at room temperature for two weeks. After two weeks, the overwintering female mites emerged from the soil and got stuck on the cards. The sticky cards were then read and the overwintering female mites were recorded. Graph 16 shows the results of soil monitoring. There was a significant difference between the conventional and reduced input program at the February 15 soil sample. There were more overwintering female mites coming from the conventional than from the reduced input. There were differences in the number of overwintering female mites in the February 22 soil sample, but the differences were not significant. The soil samples for March 15 and 22 did not show any significant differences in overwintering female mites.

Graph 16. Kern Co. Average number of overwintering female mites in soil samples taken on February 15, February 22, March 15, and March 22.

In the 1999 growing season, mites were monitored in Nonpareil and Butte varieties in the PMA orchard every other week from mid-April to mid-May, then weekly until the end of August. Both conventional and reduced input blocks were checked until mid-August, when only the reduced input blocks were monitored. Five trees per block were selected at random from the south and north ends of the plot one week, then along the center road the next week. Five leaves per tree, mostly from the lower interior portion of the tree, were examined initially; when weekly monitoring began in mid-May, ten leaves per tree were checked, half from the interior and half from the exterior of the tree. Leaves were pulled at approximately head height from all around the tree and both upper and lower leaf surfaces were examined with a hand lens for web spinning spider mites (adults, immatures, and eggs); predatory mites (adults and eggs); and sixspotted thrips. The presence/absence method of counting was used, indicating the number of leaves out of five or ten leaves where mites were seen, not the actual number of mites. Also noted were presence of European red mite, lacewing eggs and larvae, substantial webbing or multiple mites on leaves, and any other information of interest.

For the 2000 growing season, leaf monitoring for mites on Nonpareil and Butte varieties began in mid-April. Five trees were selected at random from the south and north ends of the plot one week, then along the middle avenue the next week. Ten leaves were selected from each tree. Initially, only interior leaves were selected, however, by mid-May, half of the leaves were selected from the interior and half from the exterior of the tree. Until mid-May, leaves were examined in the field with the use of a hand lens. From mid-May through the first of August, leaves were brought back to the lab, in an ice chest, and examined under a microscope. The presence/absence method of counting was used, indicating the number of leaves out of ten where web-spinning mites were seen, not the actual number of mites. Also noted were presence of European red mite, predatory mite and sixspotted thrips.

The mite data has been plotted on Graph 17 for 1999 and Graph 18 for 2000. These two graphs show two different mite situations. This really demonstrates that mite control cannot be done by calendar sprays. It has to be done based on monitoring. In 1999, mites did not appear until July 7 and increased to a treatable level on July 19. At this time, the conventional program was treated with Omiteâ (every other middle) at four pints per acre. This spray was very effective and by August 4, the mites were under control. The predator mites were not released in the reduced input program until the web spinning mite population increased to a food supply level which was reached on July 19^th. At this time, 2,500 predatory mites per acre were released. At the beginning, this release did not appear to control the web spinning mite infestation. Therefore, another 2,500 release was made August 11^th. After this second release, web-spinning mites did become under control.

In the 2000 season, the web spinning mites appeared very early in the season (Graph 18) and decreased at the end of the season. The mite population never reached a treatable level. Nevertheless, the conventional program was treated every other middle with Omiteâ at four pints per acre. This spray crashed the mite population through the end of the season. Predatory mites were released in the reduced input program at a rate of 2500 mites per acre. There was only one predatory mite release and it was done at the same time as the Omiteâ spray. The 2000 growing season was a cool one and a miticide spray was not needed for mite control.

Graph 17. Kern Co. Percent of leaves infested with web spinning mites during the season in both conventional and reduced input programs.

Graph 18. Kern Co. Percent of leaves infested with web spinning mites during the season in both conventional and reduced input programs.

Peach Twig Borer Emergence

PTB is a key pest in almonds. In some years, it can be more damaging than NOW. In the future, growers may not be able to use organophosphate (OP) sprays for its control. At the present time, however, there is an alternative for OP. The alternative is Bacillus thuringiensis or Bt. For Bt sprays to be effective, one needs to determine PTB emergence, or when the PTB larva leaves the hibernacula.

The PTB emergence curve was determined for the PMA orchard for 1999. The procedure was based on collecting rust-colored hibernacula (minute chimney-like piles of frass and sawdust) from crotches (branch angles) of trees. With a grafting knife, a pie-shaped wedge containing the hibernacula was cut from the crotches and placed into a vial. Ten hibernacula were collected per block. Under the microscope, the hibernacula was opened with a probe and the presence or absence of the larvae was noted. Absent larvae meant it had emerged. Therefore, emergence was determined by the number of absent larvae. The weekly samples were taken from early February to mid-March. Table 3 shows the percent emergence of PTB and bloom development for 1999. Unfortunately, we were unable to replicate this data for 2000 because we were unable to find hibernacula.

Table 3. Kern Co. Percent of PTB emergence and percent of bloom on Nonpareil at different dates from both conventional and reduced input spray programs.

The data on Table 3 tells us that PTB emergence does not develop at the same rate and time as the bloom. Therefore, the proper timing of Bt spray (at 50, 80, and 100%) must be based on PTB emergence.

Ant Management

Ants can cause more damage to almond meats than NOW and PTB. Orchards that are harvested early and/or with a good cover crop in the middles are most susceptible to ant damage.

The hot dogging method was used to determine the level of ant activity within each block. A half-inch hot dog slice (Bar-S brand containing beef, pork, and chicken) was placed in a snap-cap vial; 15 vials were placed in each of three rows per block, with five vials in the center of the middle and five vials along each berm. After walking in 15 trees, vials were dropped every 11 trees. Vials were distributed in the orchard during early morning ant activity for a duration of two hours, then picked up and stored in the freezer until counting. Sample processing involved removing ants from the hot dog and vial by washing them into a large petri dish for counting. All ants per vial were individually separated and counted.

Graph 19 and Graph 20 show the ant population at three sampling dates during the growing season. In both years, 1999 and 2000, the ant population was higher in the reduced input than in the conventional program. The reason may be due to the fact that the conventional programs received organophosphate sprays during the dormant and hull split period. The preharvest sprays of Clinchâ and Lorsbanâ did not appear to have a dramatic effect in the control of ants.

Graph 19. Kern Co. Average number of ants per vial on both conventional and reduced input programs in 1999.

Graph 20. Kern Co. Average number of ants per vial on both conventional and reduced programs in 2000.

Bloom

Bloom is a very susceptible disease period in almonds. During bloom, almonds are susceptible to blossom rot, brown rot, green fruit rot and shothole disease. All these diseases require moisture to become a problem. Therefore, if one can predict rain or fog, we will be able to predict diseases. It is a common practice to apply two fungicide sprays: one at the onset of bloom and another at full bloom. These two sprays provide adequate protection to almond orchards in most years.

In 1999, Sonora was the only variety that received a fungicide spray at full bloom. The fungicide was Rovralâ at one pound per acre in 200 gallons of water. The spray was applied to every other middle. This spray was enough to provide protection for bloom diseases. In 2000, the whole PMA orchard was sprayed with tank mixture of Captanâ (5 pounds) and 1.25 pounds of TopSinMâ in 200 gallons of water. The spray was applied to every other middle. This spray was effective in controlling bloom diseases in the orchard.

Irrigation Monitoring

Mite problems in an almond orchard can be predisposed by poor irrigation practices that create tree water stress. Irrigation practices in the orchard were monitored with weekly pressure bomb readings. Readings were taken on two trees in each 20-acre block. One tree was located on the north side of the block, the other on the south. In both cases, this was the third tree in from the road. In the morning, a small plastic-lined foil bag was used to cover a lower canopy leaf that was close to the trunk or main scaffold. Measuring took place at midday, usually about 1:00 p.m., when evaporative demand was at its peak. The leaf was removed from the tree and the end of the petiole cut with a razor so it had a uniform flat surface to view with a hand lens. The leaf was placed in the chamber with a small amount of petiole exposed. Measurements are made by raising the pressure in the chamber until water begins to come out of the xylem.

The pressure bomb measures the water tension in the xylem. Then, by knowing the temperature and relative humidity when the readings were taken, one can determine what values to expect for a fully irrigated almond orchard. Graph 17 shows that the orchard (conventional and reduced input programs) has been irrigated well. In 1999, the orchard was maintained around the mild stress level. However, in the 2000 season, the orchard was maintained below the mild stress level.

Graph 21. Kern Co. Mid-day stem water potential of trees in conventional and reduced input program for the 2000 and 1999 growing season.

The Leaffooted Bug (Leptoglossus clypealis)

Some years, the leaffooted bug has been reported to be an insect problem in Fresno County. In Kern County, it has never been a serious problem in almond orchards. This year, however, it became a serious pest in many Kern County orchards, including the PMA orchard.

In the spring we decided to evaluate the damage of the leaffooted bug in three main varieties in the PMA orchard. Ten, 30 nut samples were gathered at random from two blocks of conventional and reduced input programs for three varieties; Sonora, Fritz and Nonpareil. The samples were evaluated for stings on the hulls (outside), inside gumming and stings on the kernel. The results can be found on Table 4.

The Sonora variety appears to be the most attractive to the leaffooted bug. It had a greater percentage of outside stings, inside gumming and kernel stings than any other variety in both conventional and reduced input programs. However, the percent of damaged nuts was higher in the reduced input than on the conventional. The Fritz variety was second to Sonora and the least affected by the leaffooted bug was the Nonpareil.

Table 4. Kern Co. Percent of nuts showing outside stings (hull), inside gumming, and kernel stings in Sonora, Nonpareil and Fritz.

Outside Inside Kernel

Stings (Hulls) Gumming Stings

Program Variety % % %

Conventional Sonora 20.5 12.5 6.5

Fritz 9.5 6.0 5.0

Nonpareil 1.5 0.0 0.0

Total 31.5 18.5 11.5

Reduced Input Sonora 24.5 27.5 20.0

Fritz 6.5 22.0 0.0

Nonpareil 3.0 0.0 0.0

Total 34.0 49.50 20.0

Orchard Nutrition

The nutritional levels of both conventional and reduced input programs have been monitored by leaf samples taken in June-July every year. Three sets of 100 leaves samples are taken from both the conventional and reduced input programs. The samples are washed in distilled water, air dried, ground through a Wiley mill and sent to the ANR Laboratory at UC Davis. Table 5 shows the nutrient levels for the past two years.

There are no nutritional differences between conventional and reduced input program. This was expected since the fertilization program has been the same for both conventional and reduced input. However, there are two nutrients of concern, nitrogen and boron. The nitrogen in 1999 was very high; however, it did decrease in 2000. The high nitrogen is due to the age of the orchard, which is young and has not come into full production. The boron levels are marginal. They need to be around 40 to 50 PPM. The grower applied four pounds of Soluborâ per acre after 2000 harvest.

Table 5. Kern Co. Tree nutrient levels for 1999 and 2000 in the conventional and reduced input programs.

Yields of Nonpareil and Butte from both conventional and reduced input programs have been taken to measure the influence of insect damage, cover crop and oil sprays on tree productivity. Six rows of each variety (Nonpareil and Butte) were selected from both conventional and reduced programs. The rows were selected at random and represent 21% of the Nonpareil and 26% of the Buttes in the PMA orchard. Commercial harvesting equipment was used. The nuts from each row were weighed on a 40,000-pound capacity platform scale. Two four-pound samples were taken from each load at the elevator.

Table 6. Kern Co. Kernel weight and yields (lbs./ac) from the conventional and reduced input programs.

Note: None of these figures are significantly different.

Reject Levels

Reject levels were determined from 16 different nut samples. Each block was sampled in four quadrants making our sample representative of the block. The kernels, once cracked, were examined for navel orangeworm, peach twig borer and ant damage.

Table 7 shows the percent of reject levels in the Nonpareil and Butte varieties due to ants, NOW and PTB for the conventional and reduced input programs. The total reject level doubles from 1999 to 2000 in the Nonpareil variety. Also, there were no differences between the conventional and reduced input programs. Both showed a high reject level. Let’s examine each pest. In 1999, Clinchâ was applied to both conventional and reduced input programs. In 2000, the conventional program was treated with Lorsbanâ and the reduced input program was treated with Clinchâ . Ant damage levels in the conventional program decrease in the Nonpareil from 1.86% in 1999 to 0.13% in 2000. This means that Lorsbanâ works better than Clinchâ . NOW reject levels between conventional and reduced input was not substantially different. PTB reject levels for the 2000 season was very high. Nonpareils in the conventional program went from 0.26% in 1999 to 4.40% in 2000. The increase in reject levels is hard to explain. There were low shoot strike counts in the spring and low moth catches during the season but a high reject level. The Butte variety was really infested with NOW and PTB in both the conventional and reduced input program.

A reasonable explanation may be due to poor shell seal. We found that 70% of Butte nuts had an open suture.

Table 7. Kern Co. Percent of reject levels in Nonpareil and Butte due to ants, NOW and PTB from the conventional and reduced input programs.

Summary of Conclusions

Monitoring. This practice is essential to gain knowledge of the pest and diseases in an orchard. The knowledge acquired will allow a grower to reduce pesticide usage and therefore production cost.

Cover Crops. The greatest benefit of a cover crop such as barley is an increase in water penetration. This finding has solid support in literature.

Dormant Sprays. Controls San Jose Scale and ants but it does not control peach twig borer. It was a general belief that organophosphate in the dormant spray controlled PTB. This study doesn’t support this belief. However, for two years, the organophosphate decreases ant populations.

Winter Sanitation. Winter sanitation plus an early harvest reduces NOW damage. There were very low reject levels in 1999 and 2000 due to excellent sanitation.

In Season Sprays. Hull split spray has no value in controlling PTB and/or NOW in a clean orchard. In fact, one can create mite problems with in season organophosphate spray.

Mite Control. It is important to keep an orchard well irrigated. This will decrease the predisposition of trees to mite build up. Monitoring is a must for mites. It can save unnecessary spray.

Shell Seal. Poor shell seal can lead to high NOW and PTB reject levels. Poor shell seal may be a function of high nitrogen level, excessive irrigation and low temperatures during spring and summer.

Appendix A

Vetsch Reduced Input Trial Systems comparison 1999-2000

Appendix B

2000 Trefoil Insectary Cover

1999 "BIOS Insectary Mix Crop Mixture

Common Name %By Weight in Mixture Common Name % By Weight in Measure

White Sweetclover 10 Birdsfoot Trefoil, Broadleaf 48

‘Common Vetch 17

Birdsfoot Trefoil,

Subterranean Clovers 20 Narrowleaf 6.5

(3-4 Varieties)

Crimson Clover 4.0

Crimson Clover 8.3

Sub Clover 2.0

‘Nitro’ Persian Clover 5

Hard Fescue 2.0

Cereal Rye 8.3

Red Clover 1.3

Triticale 8.3

Sweet Alyssum

Barley 8.3

Little Burnet

Sweet Alyssum 0.83

California Orange Poppy

Tidy Tips 0.83

Baby Blue Eyes

Coriander 1.7

Strawberry Clover

Celery 0.83

White Yarrow

Bishop’s Weed 0.83

Toothpick Weed 0.83

Bee Phacelia 8.3

Yarrow 0.83

Kern County Pesticide Summary

Kern County is one of the largest almond producing counties in California. Since 1990, approximately 15,000 new acres have been harvested, increasing Kern county to almost 80,000 harvested acres. This information is available through the California Agricultural Statistical Service (CASS) via the World Wide Web. Chart 3.1 depicts the amount of harvested almond acreage in Kern County 1990-1998.

Chart 3.1. Harvested Almond Acreage in Kern County 1990-1998

Chart 3.2 depicts the amount of harvested acreage and the pounds of organophosphates applied per acre. Despite the amount of harvested acreage increasing, the amount of organophosphates applied has reduced. This is a positive trend. The organophosphates used in this report are azinphos-methyl, diazinon, chlorpyrifos, methidathion, parathion, naled, phosmidion, and phosmet.

Chart 3.2. Organophosphates applied in Kern County 1990-1998.

Carbamate use in Kern county has fluctuated over the past nine years. Chart 3.3 depicts the pounds of carbamates applied per acre in Kern County. With the total amount of acres increasing and the amount of carbamate applied dropping in 1998, shows that carbamate use per acre is decreasing in Kern county.

Chart 3.3. Pounds of carbamates applied per acre in Kern County 1990-1998.

Pyrethroid applications increase from virtually none in 1990 to approximately 260 in 1998. However, the amount of harvest acreage rose by approximately 15,000 acres in this time period. Chart 3.4 shows the number of applications of pyrethroids per acre in Kern County from 1990-1998.

Chart 3.4. Pyrethroid Applications per acre in Kern County 1990-1998.

Pounds of Bt applied in Kern County rose steadily from 1990-1995 but then began to fluctuate. Chart 3.5 shows the pounds of Bt applied in Kern County from 1990 to 1998.

Chart 3.5. Pounds of Bt applied in Kern County 1990-1998.

Despite the fluctuations in the use of organophosphates and carbamates and the steady increase in pyrethroid applications, the amount of acreage has also risen steadily in Kern County. The rise in acres must be addressed in viewing these pesticide use reports. This remains to be the case when viewing the fluctuations of Bt use.