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(BASIC) Deke to Sanders June Synopsis
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Kern County BASIC Pilot Program

June, 2001

At Rodger and Sandy Sanders’ Old River Farms on Lindsay Rd in Bakersfield we are observing 60 acres of certified organic Pima cotton grown by low–input practices. During June we were counting populations of insects in each quadrant of the field and in the surrounding vegetation by 100 sweeps with the sweep net and 100 standard sucks by the D–Vac vacuum insect net sampling method and visual inspection. Our reports built on those of May in which the key beneficial insects were introduced. We did complete counts of the vacuum samples to determine all of the species present in the natural enemy complex associated with each pest.

 

Report to the Sanders for June 6/7

Field Observations:

Habitat planting has sprouted, corn Sudan sunflowers etc. Alfalfa hay has been cut leaving 7 strips of uncut alfalfa in bloom starting from the south to half way is solid cut. 5–ft. strip swept with net. Each uncut strip is slightly wider going north until the last strip, which is a full border. The insects have moved away from the cotton plot migrating into strips, 1 through 7 with increasing population density. (most in %1 and least dense in final N Border).

D–Vac:

Sample was taken from the last strip. The larger insects and leaves were sieved out and examined in the field. The tiny immature forms were winnowed through the sieve screen to obtain a alcohol sample to show any Trichogramma egg parasites of moths and butterflies, Scelionids that are known to attack Stinkbug eggs, Trissolcus spp. and Mymarids that attack the eggs of lygus, Anastis aeoli. The sample will also make it easier to find the immature forms of all of the NEC (natural enemy complex) in this organic unsprayed alfalfa ie. the good bugs found and pictures of last weeks report, May 24 & 25. Gymnosoma (Tachinid fly)on adult Says Stink bug was seen. Stink bugs were the only potential pest besides lygus. The populations were crowded into the alfalfa strip left standing. This gives the appearance of being a high population in strip #1 but is less in strip # 7 which is wider and at the farthermost end of the 90 acre field.

D–Vac sample was also taken from SE corn planting site and 40 cotton plants vacuumed. There were two species of Trichogrammatidae (wild, natural) in the alfalfa. lygus egg parasite and all stages of big–eyed bugs, damsel bugs, Assassin bugs, ladybugs, etc. chasing the potential pests.

Analysis of effect of hay cutting:

Essentially, the cutting process has driven all flying insects away from the sample field. The field east of this alfalfa has not been irrigated (start this week). This north end of this check (non release field) is adjacent to the concentration of insects in the alfalfa. However, this will probably not matter since the lygus like alfalfa better than cotton. Stinkbugs like alfalfa seed and will stay in the alfalfa too. There are no spider mites or aphids and plenty of beneficials to control them as well as the lygus and the other potential pests present in the alfalfa at this time.

Releases:

100.000 Trichogrammatoidea bactrae were colonized in the Sanders cotton field. Corn mix was planted in three corners NW, NE & SE to provide habitat trap for worms and evaluate Trichogramma on corn earworm and green lacewing population density. We are enclosing a picture of Trichogramma life cycle. Flood irrigation started over a week ago on east side is being completed June 7. The drip line to our habitat is turned on each day and off at night.

 

The Sanders – June 13–15, 2001

Field Observations:

The cotton is now 6 to 10 inches tall with one full irrigation completed. This is Pima cotton. There is a history of Silverleaf whitefly in this field that never received any pesticides previously except sulfur for mites. This must be a good year for the farmer as far as the whitefly pest, since we have not been able to find any yet this year. We are fortunate to have started our project in a relatively low pest year when there are low populations of thrips, aphids, mites, lygus and worms (except for the cabbage looper leaf feeding worms).

D–Vac:

Samples were taken to see where the NEC sought refuge from the stubble field. The cotton was being irrigated in the meantime. The alfalfa will be watered after the second cotton field. It appears that the insects that could fly went to the cotton. The concentration in the seven strips forced them to follow the hay before going to the cotton. We have sampled the cotton and the alfalfa adjacent to the cotton through the first cutting of alfalfa and the cotton is ok so far. The extraordinary numbers of cabbage looper moths observed flying and lesser numbers of bollworm and beet armyworm moths is a concern.

Our samples of alfalfa have shown naturally occurring adult Trichogramma not to be present except at Sander's unsprayed alfalfa hay. This important parasite normally over–winters on eggs of the painted lady butterfly (this host is common laying eggs all winter on the Malva weeds) and over–summers on alfalfa butterfly eggs. Both of these alternate hosts are present in higher than normal densities around Old River Road than at Sanders' untreated alfalfa, near Maricopa. The difference appears to suggest that the use of CCC in both alfalfa and other crops and the monocultures created by herbicides (the non–availability of few if any flowering plants) in the plantscape as compared to grains and wild sunflowers and blooming alfalfa hay fields that receive no CCC.

Habitat:

Much of the research supporting our point of view about the value of unsprayed alfalfa was carried out in this very area of southern San Joaquin Valley in and around Old River Road. Our experience has shown that alfalfa still supports the necessary natural enemies of all pests of vegetable and field crops, especially cotton in this area.

Insectary Hedge at the Sanders Field:

The habitat enhancement planting that is designed to favor biological control of the silverleaf whitefly is now in place. 600 feet of drip irrigation line irrigates the patch in between cotton irrigation schedules. The effort involved was making a trip to the Brawley USDA Conservation Research Station to pick up the plants that Charlie Pickett of California Department of Agriculture arranged for us at no cost. The planting and irrigation system was provided with the farmer's help at minimum cost. Speed was most important in order for observation of the effects of habitat enhancement on EBPM this cotton season. The silverleaf whitefly was heavy last season in this field. We have not been able to find whitefly in either the cotton or the alfalfa so far this year.

One interesting side note is the effect on insect behavior in the insectary hedge of the dripline full of water at all times and some muddy puddles where leaks occurred. Even though the field was being irrigated, the patches of standing water and wet mud attracted many insects––particularly wasps–with concentrations of them at these sites of available water. This may favor the native western fire ant and other predators.

The thesis is clear that small modifications of the farming process and the planting of habitat enhancement patches of plants (an "insectary mix" of plants that provide flowers, nectar, pollen and other nutritional exudates, alternate host species etc., both annual and perennial, that enhance the plantscape). Beneficial insects must have the food required for their reproductive needs.

The difficulty for EBPM is the complexity of the science when dealing with the immense variability of the biocomplexity of the NEC that is difficult for implementing the processes. There isn't any money to be made by monitoring pests and telling the farmer to not spray. The products that are sold will work best when supported by a healthy NEC and will fail when the NEC has been destroyed by excessive exposure to pesticide toxins. It is complicated and it takes a great deal of trust to tell a farmer to not spray when the CCC advocates say to spray. Who does the farmer believe?

Releases:

We are colonizing a half million adult Trichogramma (egg parasites of moths and butterflies) within the limits of our budget. Cabbage looper eggs and small looper worms are feeding on the cotton leaves as I write this.

Most of these insectary grown Trichogramma (called "trichos") are released as colonies pre–fed with honey ppaper in white paper drinking cups, folded to hold them as a colony long enough for mating to occur before they find their way into the cotton. The honey is a substitute food that in a normal year would be supplied by aphids and whitefly, which are absent so far this year.

 

The Sanders, Thursday, June 21, 2001

Sampled 9–10:00 AM. The weekly D–Vac sample was taken at the biodiversity habitat planting site in the SW corner of the plot (Drip irrigation line was turned on.) The irrigation of the cotton was completed last week and both the habitat perennial plants that focus on whitefly management, the insectary mix annuals and the cotton show no stress. There are lots of weeds germinating as well. The check cotton field to the west that is being prepared for irrigation shows typical leaf wilt from the heat. Temperatures will reach over 100 degrees each day. The alfalfa hay field has grown back from the cutting that was harvested two weeks ago, is still without irrigation. Irrigation will be completed June 22, in the cotton across to the east from the alfalfa. Sweep samples of the alfalfa and all of the cotton reveal good sets of natural enemies, particularly the big–eyed bugs, the most effective predator control for lygus and many other soft bodied insect pests.

Staggered strip–cutting of the alfalfa planting:

starting from the south end of the field advancing to the north end (leaving 7 strips of standing alfalfa spread evenly from the middle to the north end) caused the mature insects to fly into this standing alfalfa and concentrate in these strips. This concentration of adult insects triggers reproduction of both the plant feeding insects (potential pests) and their sets of natural enemies (beneficial biological controls). The D–Vac samples and sweep–net samples revealed that lygus in particular and the predators ( big–eyed bugs, damsel bugs, minute pirate bugs) responded to this concentration of lygus prey (food). They increased their reproduction rate in proportion to this concentration of all insect life present within this small amount of alfalfa plants remaining in these strips.

D–Vac Samples:

Our observations of insect samples showed a crowding of (wingless) immature insect predators in these strips. Only, the adult insects were able to move with the cutting process. The resident immature (wingless) insects were left in the alfalfa stubble where the removal of growing alfalfa plants concentrated the prey (lygus, aphids, mites, thrips etc.) on the stubble. This increased the searching efficiency, resulting from crowding of all flightless stages of insects onto stubble gave the advantage to the beneficial predators, less food for the pest and less searching for the predators, favoring biological control in the battle of good and bad bugs in the whole alfalfa planting.

Small habitat management decision made big difference in beneficial insect ecology:

The combined effects of this slight modification of the alfalfa hay harvest resulted in favoring the reproduction of beneficial insects and reducing the numbers of their prey (all plant feeding species). The process also drove the adult insects (flyers) away from the cotton dispersing them throughout the area. It is documented that the increased reproduction of beneficial predators eventually find their prey. Food drives all of these sets of biological controls and the plant feeders alike.

Thus, this farming process or event demonstrates that small changes in farming practice can be used to increase the effective biological control of all pests of vegetable and field crop pests. Extensive research in ecologically based pest management (EBPM) has proven beyond doubt that cotton can be grown with much less use of pesticides when alfalfa hay production is managed as a resource for beneficial and a trap for potential pests.

This season is unique in that the cotton aphid, thrips and mites as well as less than usual lygus populations reside in all of the cotton blocks. Lygus adults are relatively rare species while all of the cotton worms are high density at the all other farms. We can only guess that the favorable number of big–eyed bugs and the hooded beetles seen in every sample is responsible. Aphid predators are abundant and yet aphids difficult to find. All of these predators overwintered from the large populations that occurred following last season at Sanders Ranch because Silverleaf whitefly was a pest and no pesticides other than sulfur and no herbicides have been used.

Early aphids can be a resource for growing mite predators:

The usual process of biological control systems is for the 60 or more species of predators and parasites of aphids to attract and grow the biological controls that clean up of aphids and then mite control follows soon after. All of the aphid predators are hungry and are forced to clean up the mites or starve or migrate. Most of the aphid predators will feed on mites when they no longer can find aphids. The same is true of thrips and their natural enemies. The western flower thrips, a pollen feeder, will eat mite eggs before it resorts to feeding on plant tissues. Our samples reveal many kinds of mite predators and few if any mites at this time. The lygus populations are also no threat.

Keep predators alive longer with carbohydrate food sources in a habitat:

There is the chance that many of these predators will die of old age or starvation before any new pests arrive, but we know that they can live longer feeding on plant exudates, nectar and pollen when they cannot find their prey that makes them lay their eggs. Each set of predators reproduces rapidly when their particular prey resource becomes abundant. This is the natural rule that is the basis for the biological control process. It is a "density–dependent" response that speeds the reproduction process of predator and parasite species over the prey.

Keep the insect150;plant systems functioning:

Successful biological control is based on biodiversity and biocomplexity of both plant and insect species. The principle basis for this demonstration is to find ways to increase polyculture of plants, even non–snoxious weeds that provide the food and space (habitat enhancement) to the massive monocultures of agriculture. We must provide non–sprayed patches or crops where "pesticide interference" to biological control systems is prevented. These small unsprayed plantings will keep the full sets of natural enemy complexes breeding in residence and adjacent to the market crops where they can enter the new cotton planting as soon as the first pests arrive. Ways must be found to keep insect–plant systems functioning in between crops. This is the opposite of the present paradigm, the opposite of eradication by broad–spectrum pesticides.

 

Francisco Cornejo’s Report to the Sanders for June 28 & 29

Plant growth:

The cotton plants at this field are growing slowly but has strong stems which is characteristic of Pima varieties. The plants have good color and are heavily loaded with flower buds. The plants are noticeably shorter here than elsewhere because they have been grown in sub optimal organic soil. However, these plants have the strongest stems and will likely have higher square/boll retention than the other fields. In general the plants are very healthy

Sweep net sample:

6 Lacewings

6 Lady beetles

4 Nabis

2 Oriusz

3 spiders

6 Geocoris

Some Lygus and looper larvae were seen on the plants but were not caught in the sweep net.

D–Vac analysis:

This sample had the most favorable balance of beneficials to pests. This is due to the diversity of the surrounding plantscape (;alfalfa fields, grain fields, and uncultivated rangeland). I did not find any signs of mites or aphids.

Habitat:

The nearby alfalfa field is being irrigating to start re growing. There is a good number of beneficials that will move over here.

Releases:

I released 100,000 Trichogramma most of which were already emerged.

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