Kern County Pest Management Alliance Project

Year-End Report 2002

Mario Viveros, Walt Bentley,

Peggy Schrader and Minerva Gonzalez

Introduction:

The purpose of this project was to demonstrate a reduced pesticide input versus a conventional pesticide management program in young orchards for the Southern end of the San Joaquin Valley.  This project was established four years ago in a 160 acre block which was made up of 80 acres of “hard shells” (Butte – Mission – Padre) and 80 acres of “soft shells” (Nonpareil – Fritz – Sonora).  Both “hard and soft” shell varieties were divided into two (20 acres each) conventional and two (20 acres each) reduced input management plots.  For the 2001 and 2002 season each of the plots in both conventional and reduced input were divided into dormant and non-dormant spray subplots.  This is to say we now have the following treatments:  1) conventional dormant,  2) conventional non-dormant,  3) reduced dormant, and  4) reduced non-dormant.

This report is for data obtained in the 2002 season.  It doesn’t include information from 1999, 2000 and 2001 seasons.

Cover Crops:

The barley cover crop has been selected because of the saline-alkali and poor drainage conditions of the PMA orchard soil.  The barley was seeded in every middle on both “soft” and “hard” shell blocks, at a rate of 80 lbs. per acre.  The seeding was done in December, but the seed didn’t germinate due to lack of winter rains.

Pest Monitoring:

The setup for pest monitoring was similar to the one we used in 2001.  The reason being that both conventional and reduced input management treatment was subdivided into dormant and non-dormant subplots.

San Jose Scale (SJS).  This pest was monitored using twig samples, pheromone lures and double-sided sticky tape.  The overwinter population on fruiting wood was monitored in December.  Twenty spurs were gathered from each block, concentrating on the susceptible varieties, Padre, Sonora and Thompson.  Ten spurs were gathered low and ten high on the tree.  The fruiting wood was again evaluated in March taking five twig samples in each treatment.  The adult population was monitored by placing one sticky trap with a pheromone lure in each plot.  The trap was placed on the tenth tree in from the end, and six or seven feet high in the northeast quadrant of each tree.  The trap was placed on February 11 and was monitored weekly until the end of November.  Pheromone lures were replaced every four weeks.  Adult San Jose moths were counted as well as the Encarsia and Aphytis adults.  The crawlers were monitored by using double-sided sticky tape which was placed in four trees surrounding the tree that contained the pheromone traps.  Tape was placed March 29, 2002 and was monitored weekly for presence-absence until the biofix occurred.

Peach Twig Borer (PTB).  This pest was monitored by placing pheromone traps and by larva emergence from hibernacula.  The traps were used for monitoring the adult population.  They were placed in the tenth tree in from the end, six or seven feet high in the northeast quadrant of the tree.  The traps were placed March 29, 2002 and their pheromone lures were replaced every eight weeks.

The PTB larvae emergence was determined by collecting rust-colored hibernacula (minute chimney-like piles of frass and sawdust) from crotches (branch angles) of two year old trees.  With a grafting knife, a pie-shaped wedge containing the hibernacula was cut from tree crotches and placed into a vial.  Ten hibernacula were collected from 10 different areas of an orchard located 9 miles from the PMA orchard.  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.  Samples were taken, every five days, from early February through early-March.

Navel Orangeworm (NOW).  This pest was monitored with egg traps and winter sanitation.  One NOW egg trap was placed in each plot on March 29, 2002.  It was placed in the tenth tree in from the end in the north side of the tree and six or seven feet high.  The traps were black and contained an almond meal mixture.

Winter sanitation was evaluated on February 12, 2002 by counting the number of nuts left from harvest.  These nuts are called mummies.  Forty-five trees in each plot were selected and the number of mummies were counted in each tree.

Mites.  This pest was monitored with soil and leaf samples.  The soil samples were taken in the winter and leaves were sampled during growing season.  Soil monitoring to determine the overwintering female web spinning mite began January 16, 2002 and continued with weekly samples until April 11, 2002.  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 to the cards.  The sticky cards were then read and the overwintering female mites were recorded.

Leaf monitoring for mites on Nonpareil and Butte varieties began on March 13, 2002.  Leaf samples were taken at random from five trees in each plot.  The tree location changed every week.  On one week the trees were located at the extreme ends of the orchard, but on the following week, they were located through the middle of the two blocks.  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.  Leaves were brought back to the lab, in an ice chest, and examined under a microscope.  The presence-absence method was used.  Only web spinning mites were considered.  European red, predatory mites and sixspotted thrips were noted.

On March 7, 2002, twigs were selected from trees to evaluate the movement of overwintering females.  Five twigs were gathered from five different trees in each plot.  Twigs were selected from inside of major branches and only the lower parts of the branches were sampled.  The twigs were brought back to the lab and examined under a microscope.

Ants.  This pest was monitored by the “hot dogging” method on May 14, May 31, July 1, Aug. 7 and Sept. 20, 2002.  Half-inch hot dog slice (Bar-S brand containing beef, pork, and chicken) was placed in a snap-cap vial.  These vials were distributed in the orchard in the morning when ant activity is at its maximum.  The vials stayed on the orchard floor for a period of two hours, then picked up and stored in the freezer until counting.  The ants were removed from vials by washing them on to a petri dish.  The ants were separated with a glass rod and counted.

Nutrients.  The nutrient levels were monitored by June-July leaf samples.  The samples were washed in distilled water.  They were allowed to dry and then ground through a Wiley mill.  The samples were then sent to the ANR Laboratory at U.C. Davis for analysis.

Production.  Yields of Nonpareil and Butte from both conventional and reduced input systems were taken at harvest.  In addition, yields were taken from dormant and non-dormant sprayed plots from both conventional and reduced input systems.

Treatments:

Dormant Sprays.  The conventional and reduced input systems were subdivided into sprayed and non-sprayed.  The conventional sprayed treatment was sprayed with five pints of Diazinon® plus six gallons of oil mixed with 250 gallons of water per acre.  The reduced input treatment received six gallons of oil in 250 gallons of water per acre.  The spray was applied December 18, 2002.  The complete spray program can be found in Appendix A.

Winter Sanitation.  By February 7, both conventional and reduced input treatment were mechanically shaken for mummy removal.

May Spray.  This spray was done for the control of NOW and PTB.  The reduced dormant and and reduced non dormant treatment were sprayed with Confirm® at 16 oz. per acre in 250 gallons per acre.  The PTB biofix was April 3 and NOW was April 10.  The spray was done on May 13, 2002.  At this time, we had accumulated 523 Degree-days for PTB and 307 Degree-days for NOW.

Hull Split Spray.  This spray was done on July 9, 2002, at the on-set of hull split for the control of NOW.  The conventional (dormant and non-dormant) was sprayed with Imidan® 5 lb per acre in 250 gallons per acre.

Mite Sprays.  The conventional (dormant and non-dormant) was sprayed with the following:  1) 4 gal. oil on March 21 and 28,  2) AgriMek® 10 oz. on May 12 and  3) 2 gal. oil on May 1, 2002.  Reduced-dormant AgriMek® at 10 oz plus 2 gal. of oil per acre.  Reduced non-dormant was sprayed with AgriMek® 10 oz. plus 2 gal. of oil per acre.  This was done spraying every other middle.  The other sprays were done solid.  The amount of water for all sprays was 250 gallons per acre.

Ant Sprays.  The conventional-dormant was sprayed on Aug. 7 with 4 pt. Lorsban® in 100 gallons of water per acre.  Reduced-dormant received 1.5 lb. Esteem® per acre.  Reduced-nondormant received one pound of Clinch® per acre.

Results:

San Jose Scale.  The San Jose Scale continues to increase in the plots that were left unsprayed for two dormant seasons.  During the growing season, scale was found on leaves and along the nut suture.  Also, heavy infestation was found on the spurs.  Table 1 shows the percent of spur infestation on December 10 and March 18 from treatments that received a dormant spray and non-dormant spray.

Table 1.  Percent of spur infestation on December 10 and March 18 from dormant and non-dormant treatment.

Reduced Input (oil)                                                               5                                        0

Conventional (oil & Diazinon®)                                            0                                        0

Reduced (no dormant)                                                          8                                       60

Conventional (no dormant)                                                   21                                      60

The SJS adult populations from plots that receive no dormant spray and from plots that received a dormant spray are found in Figures 1 and 2.  Figure 1 shows the adult population from plots that received no dormant spray and Figure 2 shows SJS populations that received a dormant spray.  Both show the same population pattern in the growing season.  These are two generations in both figures and both have the same population numbers.  It is important to note that SJS spur infestation is a better indicator of orchard infestation than adult population trapped on a pheromone traps.  The traps only show the presence of SJS adults.

Figure 1.  Average number of male SJS per trap, where no dormant spray was applied, from February to November.

Figure 2.  Average number of male SJS per trap, where dormant spray was applied, from February to November.

Peach Twig Borer.  The 2002 PTB emergency (Figure 3) was earlier than the emergence in 2001.  This was due to warm temperatures (Figure 4) in February.

Bloom sprays for disease control were not needed during the 2002 bloom season.  The weather at this time was warm and dry.  However, if sprays had been necessary, one could have included the pesticide Bt for PTB control since PTB emergence and bloom development coincide with each other.

Figure 3.  Peach Twig Borer emergence for 2002.

Figure 4.  Daily high temperatures in February – March for 2001 and 2002 during PTB emergence.

Figure 5 shows the adult population of PTB from February to November in the no dormant spray for both conventional and reduced input treatments.  The two populations of PTB (conventional and reduced) were the same and the same thing can be said about the dormant spray treatment (Figure 6).

Figure 5.  Average number of PTB per trap, where no dormant spray was applied, from February to November.

Figure 6.  Average number of PTB per trap, where dormant spray was applied, from February to November.

Table 2 shows the number of strikes in May.  The number of strikes was very low in the orchard.  At this level one should not expect any nut meat damage.  The Diazinon® plus oil dormant spray had twice the amount of strikes as the oil alone.  However, where no dormant spray was applied, the amount of strikes was almost double to the oil and Diazinon® plus oil sprays.

Table 2.  Average number of strikes per tree on May 24, 2002

Conventional                                     Diazinon® + Oil                                               0.15

Reduced Input                                   Oil                                                                   0.08

Conventional                                     Diazinon® + Oil                                               0.15

Conventional                                     No treatment                                                    0.25

Reduced Input                                   Oil                                                                   0.08

The percent of rejects due to PTB is shown in Table 3.  The rejects for 2002 were zero in all dormant treatments.  Confirm® was applied in May for PTB control.  This spray had no effect in reducing nut meat damage at harvest time.

Table 3.  Percent of rejects due to Peach Twig Borer damage.

Navel Orange Worm (NOW).  Mummy counts showed that all conventional and reduced input management plots had less than one mummy per tree by February 12.

The average number of NOW per trap from both non-dormant and dormant sprayed plots can be found in Figures 7 and 8 respectively.  The average number of eggs during the growing season was very low on both dormant and non-dormant treatment.  There were more eggs on the dormant than on the non-dormant treatments.
 

Figure 7.  Average number of NOW eggs per trap, where no dormant spray was applied, from February to November.

Figure 8.  Average number of NOW eggs per trap, where dormant spray was applied, from February to November.

NOW rejects can be found in Table 4.  In the Nonpareil the reject levels in reduced input was higher than the conventional.  However, the reduced input no dormant was lower than the conventional no dormant.  The reject level, nevertheless, were very acceptable for Nonpareil.  The reject levels for Butte were about the same in all treatments.

Table 4.  Percent of rejects due to Navel Orangeworm damage.

Mites.  The 2002 season was a mite year due to 100^○F days during the summer.  The mites were kept under control with oils and Agri-Mek® sprays.  Table 5 shows mite sprays treatments for 2002.

Table 5.  Mite treatment for 2002

Conventional               Diazinon® + Oil             oil 4 gal. (3/21) AgriMek® 10 oz. + oil 2 gal.(5/1)

Conventional               No treatment                  oil 4 gal. (3/21) AgriMek® 10 oz. + oil 2 gal.(5/1)

Reduced Input            Oil                                 AgriMek® 10 oz. + oil 2 gal. (5/16) solid

The results of these treatments can be summarized with the following statements.  One, there were no differences in mite leaf infestation between dormant and non-dormant treatments.  Two, mite control due to AgriMek® sprays were effective when solid rows were sprayed as well as when every other row was sprayed.  Third, plots that were sprayed with oil in the spring had significantly fewer mites than plots that were not sprayed with oil.

The average number of overwintering mites are found on Table 6.  The number of overwintering mites is not significantly different between reduced input, conventional and conventional no-dormant.  However, when we look at the totals of all dates, the reduced input had the highest amount of overwintering mites.

Table 6.  Average number of overwintering female mites per sample

The movement of mites from the orchard floor to the tree scaffolds was evaluated by twig samples.  No movement of mites was detected in any of the treatments.

Ants.  This insect can cause more damage to almond meats than NOW and PTB.  Orchards that are harvested early and/or with a good resident vegetation in the middles are most susceptible to ant damage.  The ant treatments can be found in Table 7.

Table 7.  Ant treatments for 2002

Lorsban®                                          4 pints per acre                                             August 7

Clinch®                                             1.0 pounds per acre                                        July 1

Esteem®                                           1.5 pounds per acre                                       June 18

control                                               untreated

The ant population can be found in Figure 9.  The lowest population is in the Lorsban® which was also the conventional.  This treatment gets treated with dormant oil and Diazinon®.  The Clinch® population was also low at pre-harvest.

Figure 9.  Average number of ants per sample.

Ants reject levels are found in Table 8.  The reduced input had a significantly higher reject level than the conventional.  The reason may be due to the Diazinon® in the dormant spray and the Lorsban® applied pre-harvest.  There were no differences in ant damage between reduced input and conventional in the Butte variety.

Table 8.  Percent of rejects due to ant damage.

Shell Seal.  During the 2002 season an evaluation was made to try to see if crop load had an affect on shell seal.  Trees were selected based on a light, medium or heavy load.  Ten trees were selected for each crop load for a total of thirty trees.

Initially, 5/28, 6/10 and 6/27, the nuts were sliced into three sections and examined to see if a difference in shell development could be observed.  On the last three dates, 7/19, 7/30 and 8/19, the nuts were examined for any split in the suture.  All samples were picked from the tree with the exception of the final sample, which was picked off the ground.

One hundred nuts were checked for shell seal at the time of harvest.

Yields.  The yields for Nonpareil and Butte are found in Tables 9 and 10 respectively.  There were no significant differences between any treatment.

Table 9.  Weight per kernel and pounds per acre for Nonpareil.

Table 10.  Weight per kernel and pounds per acre for Butte.

Orchard Nutrition.  There has been no differences in orchard nutrition between conventional and reduced input.  There is no reason to see a difference since both management styles have been managed the same.  The nutrition status of both management styles are found on Table 11.

Table 11.  Tree nutrient levels for 1999, 2000, 2001 and 2002 in the conventional and reduced input programs.

Appendix A

Dormant

May/Hull Split

Mites

Ants

  *Error in spraying the hard shells

**Error in spraying
 

Acknowledgements

We wish to thank Thomas Vetsch of Vetsch Farms of California, Inc. for providing and maintaining the study site, and for providing labor when needed.  We appreciate the donation of predatory mites by Matt Billings of Sterling Nursery, and Clinch® and financial support from Novartis.  This study was supported by a grant from the California Almond Board Pest Management Alliance.  Thank you for your support.