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(BASIC) June 13–15 Report
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For All Growers: Trip Report June 13–15, 2001

Kern County BASIC Pilot Program

Deke and Francisco Cornejo made and compiled the report.

 

Antongiovanni – June 13–15, 2001

Field Observations:

This cotton plot has the most diverse set of NEC of the Old River Road group of cooperating farmers. The source of beneficial insects is probably the safflower. The cotton is adjacent to safflower, a water melon field and unknown harvested vegetable crop with lot of weeds and Johnson grass and other plants in bloom on east and south sides. There have been no pests until this week when cabbage loopers swarmed into the cotton from the alfalfa hay harvest. These moths feed in the alfalfa bloom a few days and fly from the stubble after cutting into the cotton to lay their eggs. The high numbers of cabbage looper moths that are flying in all cotton fields at night are depositing eggs and small larvae are hatching. The cotton north of this plot has a spray rig applying CCC, possibly selective Bacillus thuringiensis (Bt) to the cotton on 6/14 & 15 while we were making tricho releases. The predator complex is composed of big–eyed bugs, damsel bugs and Hooded beetles all of which will feed on these eggs and small larvae.

D–Vac Samples:

We have sampled Hyposoter exigua., a small wasp parasite, that attacks half inch long looper worms. Sixty percent have been reported in the literature. They are Nature’s second line of defense against cotton worms. However, the several species of beneficial tachinid fly, especially Voria ruralis, that yields three to five flies from each large looper worm that it attacks have not been seen so far. These important beneficial flies will be too few and too late for lack of an unsprayed refuge and from pesticide interference.

Habitat:

The habitat enhancement blooming plants are necessary for this largest group of beneficial insects that control cotton pests. The habitat refuge planting that we are seeding may be too late to help us at this moment, however, we will be monitoring for the presence of these important biological control organisms to discover when they will discover these looper pests. Monoculture without unsprayed year–round flowering plant sources limits the use of EBPM and IPM pest control strategies.

The reduction of the need for conventional chemical control (CCC) is dependent upon having the natural occurring beneficial organisms close by to where the cotton is being grown. The natural suppression of pests occurs where and when most of the known many sets of beneficial insects are provided for by planting a diversity of habitat enhancement plantings, corn, Sudan, Sorghum, flowering safflower and sunflowers, that act as a trap and a refuge for both the pest or an alternate host species. Diversifying plantscape is to optimize the diversity of insect and mite species growing in the plantscape. The cutting process of alfalfa hay is also somewhat involved. It is a lot like recovery from drug addiction. It takes a change of life style to go through the pain of withdrawing from CCC.

Releases:

We made our second release of "tricho" egg parasites. We probably need many more than the 200,000 per week that is scheduled in our budget.

 

Banducci – June 13–15, 2001

Field Observations:

It is possible that enough of the leaf feeding loopers in this field will escape the biological control suppression by trichos, Hyposoter parasites and the insect predators, but they will attract enough black birds to control them. Spraying of all the surrounding cotton fields will concentrate these voracious predators of cotton worms into this one unsprayed field, where the only worms (food) is still present. Moths and small worms can be tolerated but too many large worms can defoliate cotton. The natural virus disease is the final epidemic that destroys loopers. The selective pesticide Bt will kill loopers, but it costs money and also limits the reproduction of biological control organisms because the food source (looper worms) is eliminated. A tolerable level of leaf damage will be extremely valuable to grow the Hyposoter and Trichogramma wasps that will control future pests like beet armyworms, cotton bollworm and salt marsh caterpillars.

Habitat:

The number of lygus in the safflower is less than usual and they appear to be staying in the Safflower at this time. Minute pirate bugs are feeding on flower thrips in the safflower but there is a lack of cotton flowers, thrips and pollen to feed the minute pirate bugs in the cotton. Minute pirate bugs are heavy in the tasseling corn at Banducci. They are the main predator of earworm in corn which is the cotton bollworm. The large numbers of big–eyed bugs, lacewings and Hooded beetles that grew on prey in the safflower are now migrating from safflower to cotton. Food drives these biological control systems. The looper eggs will be the only food for them. There is no other host present in the numbers to feed these predators at this time. It is the story of "if you don't have cake, they will eat the broccoli". If there are no lygus, aphids, etc, they will eat looper eggs and larvae or eat each other.

I would prefer to grow beneficials that attack worms in an unsprayed alfalfa field or other protected habitat refuge crop. For comparison, cabbage loopers are present in very low numbers at Sanders and Reynolds. Banducci cotton plot is unique for the large diversity of plantings and staggered corn plantings. The adjacent alfalfa field to the south has many beneficials and some worm pests. Alfalfa butterfly worms dominate, with a few bollworms and beet armyworms. Looper moths and alfalfa butterflies are common, but other moths are between generations. Looper eggs are readily found but few of them hatch or grow to be one day old or larger up to half inch long worms. Loopers don't defoliate until the later growth stages just before pupation occurs. We hope that they will continue to be eaten by predators as soon as they are deposited on the cotton and the next generation will be reduced. No corn earworm eggs are seen in the corn. It is between flights of the corn earworm moths.

Green lacewings adults are very common in all of the fields, but very few if any eggs are seen in this cotton even though at Banducci's sweet corn that is in tassel stage starting to silk and located within his cotton field has lots of lacewing eggs. It isn't the weather but it probably is the lack of a pollen source that is necessary for these overwintering adult lacewings to start laying eggs. Several adult lacewings were placed in a sack to see if they laid any eggs overnight. We confirmed that these 25 adults laid no eggs.

The lacewing adults that overwintered in the safflower went into winter diapause last fall and it will take protein from pollen to trigger egg laying. We should have planned to release lacewing eggs from the insectary rearing since it is essential to trigger egg laying. Or we should let nature provide a few aphids, for honeydew and flowering plants in a refuge. Our corn–Sudan habitat planted patches will eventually attract adult lacewings but egg laying will start when pollen from corn and various (weed) plants supply it. Cotton flowers are now prevalent in this plot and lacewing egg laying will begin soon from this pollen source. The large planting of corn in this area will soon be in tassel providing pollen but the timing is wrong for this plot this year.

The south side of this cotton plot has trees and farm equipment that the Polistes paper wasps, mud dauber yellow jackets and others use for nests which they stock with worms (cabbage loopers). They have increased in numbers dramatically this week 6/15.

D–Vac Samples:

The worms seen in the alfalfa are small and the next bollworm/earworm flight will not be for 3 to 4 weeks. There is no evidence of worms in the silk and minute pirate bugs (the best thrips and worm egg predator) are searching the silk strands for eggs. The favorable ratio of predators and parasites to pests are keeping them under control. Natural populations of trichos are sampled as part of the NEC in the untreated alfalfa hay as well. No aphids and few flower thrips and fewer mites and many mite predators make up the NEC.

 

DeStefani – June 13–15, 2001

Field Observations:

This Roundup Ready cotton has near perfect weed control and monoculture. Loopers deposited lots of eggs and some light defoliation has occurred but the plants are growing very vigorously, outgrowing the damage in all cases. The prevalence of looper eggs have led us to colonize trichos three times (weekly) in the hopes of establishing this valuable egg parasite of moths and butterflies. The insectary–grown wasps were swarming in the cups on two releases made during the irrigation.

Habitat:

Adjacent alfalfa to the south of the plot and other alfalfa hay has been harvested and irrigated. The hay field to the south was cut driving the insects into the unirrigated half of the adjacent cotton where the moths and other insects were congregated; held there by the irrigation process starting on the north side of the cotton plot. There is evidence that tricho releases are best when the cotton is being irrigated since the moths seek the watered cotton. The NEC insects do not all remain in the cotton. Experiments have shown that lygus adults migrate to cotton from cut alfalfa and return to alfalfa when it grows back after irrigation restarts the next alfalfa growth cycle. These insects do some damage since the adults deposit and leave eggs and nymphs but the adults mostly seek alfalfa in preference to cotton and return to alfalfa in 7 to 10 days, depending on the time it takes to start the new growth cycle. There is one generation of lygus per cutting cycle of alfalfa.

It is well known that insect populations move from the cutting process into the adjacent uncut portion in a continuous manner as the field is cut. Thus lygus and the other adult insects can be driven to one end or the other of a field by the cutting pattern or process. The hay harvest at Sanders was one way of many that this farmer devised to drive the insects away from the cotton and at the same time concentrate the insect populations in seven uncut strips at the distant half of the 90 acre field. The first strip left was only a cutting swath wide and the width of each strip of uncut alfalfa increased one swath until the last remaining standing hay was more like a border width. The cutting began on 6/7 and upon our return on 6/13 the uncut strips were finally harvested and all of the bales were removed from the whole field.

The mowing process therefore concentrated the predators on the stubble and within the strips of flowering uncut alfalfa for a time and this favored the predators of the NEC. With less alfalfa for the plant pests to hide in, the preponderance of predators speed up their reproduction and many of the mobile adults find their way to the cotton. The full crop of alfalfa was harvested from the whole field in time to move the sprinklers, ready to irrigate the alfalfa in sequence to other fields on the farm. There was minimum extra effort and no disruption in scheduling of the farming process for the whole ranch and no loss of market quality or yield of hay.

We have planted the corn, Sudan and patches of flowering plants but they have not germinated yet. Possibly the Roundup application is too toxic for these plants?

 

Reynolds and 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 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 paper 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.

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