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(BASIC) July 12 & 13 Report
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For All Growers: Trip Report July 12 & 13, 2001

Kern County BASIC Pilot Program

Deke and Francisco Cornejo made and compiled the report.

 

Antongiovanni – E. Bakersfield – July 12 & 13, 2001

Field observation of biological control by pathogens:

We noticed several looper larvae that had died from disease caused by nuclear polyhedrosis virus (NPV), granulosis virus (GV) or fungal pathogens. Review of the technical literature point that "in general, diseases reach substantial levels in a population only when conditions are humid and densities are high", both of these conditions were present at this field. The lush growth of this probably lead to the high population of this particular pest, but also fostered the high numbers of the beneficial insects that are present on the farm. Since loopers are not considered as serious a pest as bollworm, the ‘outbreak’ of loopers has developed the insect arsenal necessary to prevent a bollworm problem in the future. This is an example of the dividends that can be gained by letting a lesser pest outbreak resolve itself naturally. Developing an insect habitat here would further enhance biological control of pests.

Plant growth:

There has been lush growth, but extensive chlorosis on the top leaves in this field last week is now seen on the middle leaves. The lower leaves have less damage. The top leaves (i.e. new growth) appear to be healthy. This pattern suggests that the chlorosis is due to a foliar application applied 2 or 3 weeks ago. We also noticed the same chlorosis in the field to the north of this one. The results of the petiole analysis may shed some light on the cause of the observed chlorosis. Thus far we haven’t been able to discuss this situation with the grower. The only fact that we’re certain is the chlorosis is unrelated to insect activity.

Sweep net samples:

Only north half of field was samples because other half was being irrigated.

Many big–eyed bug nymphs

Ants

Several lady beetles

Several lacewings

4 hooded beetles (=Notoxis spp.)

1 Lygus

4 whiteflies

1 small aphid colony

Several minute pirate bugs

2 Assasin bug nymphs

1 Damsel bug

5 1 day old loopers

We also noticed several yellow jackets (=Polistes) and Tachinids, both of which are predators of loopers.

In general the pest situation this field is doing very well.

D–Vac analysis of 50 plants:

Only 3 Lygus adults were found in the presence of many big–eyed bugs indicating the immature Lygus are being eliminated before becoming adults. Other potential pests found were ants, cucumber beetles and whiteflies. There are plenty of generalist predators (assassin bugs, Sineid spp., hooded beetles, wolf spiders and minute pirate bugs) to prevent them from becoming pests.

Habitat:

We are concerned that the Sudan grass planted several weeks ago never germinated. This is very likely due to the use of Pounce. Having seen how many weeds were in this field before the cotton became established, herbicide use was justified. However, in order to establish beneficial habitat some area must be set aside for this purpose. Usually the best locations are along the edges of fields. Sudan grass borders would provide protection against spider mite outbreaks. A perennial hedgerow of drought tolerant plants like the one at Sander’s field on South Lake Rd would provide a refuge for the Eretmocerus that will be released. The main benefit of establishing diverse habitat is the stabilizing effect it has on natural pest control by providing natural enemies alternate food sources and refuge.

Releases:

We made releases of 100,000 lacewings and 400,000 Trichogramma mainly because we observed loopers in the past and a few whiteflies and aphids this time. We will start releasing Eretmocerus californicus to keep the silverleaf whitefly at the low densities that they are now.

 

Banducci – W. Bakersfield July 12 & 13, 2001

off Green Rd.

Field observations of biological control by disease:

This farm has shown tremendous increases in the beneficial organisms that are keeping lygus and loopers under control. As we reported before there were high number of loopers larvae on two sides of this farm. Last week we noticed a significant decline in their numbers due to several general predators (birds, big–eyed bugs, lacewing and Hyposoter–a common looper parasite*. This week another mortality factor appeared– –disease. We noticed several looper larvae that had died from disease caused by nuclear polyhedrosis virus (NPV), granulosis virus (GV) or fungal pathogens. A study showed that, "In general, diseases reach substantial levels in a population only when conditions are humid and densities are high." Both of these conditions were present at this field. The lush growth probably led to the high population of this particular pest, but also fostered the high numbers of the beneficial insects present on the farm. Since loopers are not considered as serious a pest as bollworm, the ’outbreak‘ of loopers has developed the insect arsenal necessary to prevent a bollworm problem in the future. This is an example of the dividends that can be gained by letting a lesser pest outbreak resolve itself naturally. Developing an insect habitat here would further enhance biological control of pests.

Sweep net samples:

North and south sides of field sampled the length of field.

6 Big–eyed bugs (=Geocoris) mostly adults, some nymphs

3 Spiders

3 Damsel bugs (=Nabis)

1 Tachinid fly (a worm parasite)

2 Minute pirate bugs (=Orius)

Several thrips

Black hunter thrips

1 Assassin bug (=Zelus) nymph

lacewing adults

1 small looper larva

D–Vac analysis from 50 plants:

All life stages of big–eyed bugs (2 species) were present along with immature stages of assassin bugs. The number of beneficials far exceeds the number of pests. One large Lygus nymph, some 1 day old loopers, 1 aphid and a few whiteflies were the only pests seen. The fact that only certain life stages of the pests are present with most of the life stages of the beneficials implies the beneficials are eliminating the other life stages of the pests. Also another food source (probably leafhoppers since they have been found in every sample taken) is keeping the good–to–bad bug ratio high. Other assorted beneficials seen were spiders, robberflies, six–spotted thrips, red and black myrids (egg parasites).

Hedge for whitefly control:

We have planted a hedgerow consisting of several drought tolerant plants that provide a refuge for the parasites (Eretmocerus spp.) of silverleaf whitefly. One or two whitefly were seen so we will be releasing some Eretmocerus californicus. Several dragonflies and damselflies (both voracious general predators) were seen flying around, as well as some Hyposoter pupae and Polistes wasps. Also noted were lacewings eggs and egg masses of Zelus at different locations through the farm. Along the dirt driveway, near of the cement ditch ground beetle (Collosoma spp.) larvae and adults (which prey on large worms) were also seen.

 

DeStefani – W. Bakersfield July 12 & 13, 2001

off Buena Vista Rd.

Sweep net samples:

The north side of the field was sampled the length of the field.

12 Big–eyed bugs (=Geocoris)

3 Minute pirate bug (=Orius)

2 Damsel bugs (=Nabid)

3 Spiders

1 Collops beetle (=Collops spp.)

1 Assassin bug (=Zelus)

Many lady beetles and lacewings

D–Vac analysis from 50 plants–

A diverse assortment of beneficial insects was collected along with a few pests. The insect diversity is a reflection of the habitat diversity (corn, melons, weeds, trees and neighboring alfalfa fields) around this field. Although ~10 half grown loopers were found, several Apanteles marginalventris )a parasite of small worms) were present as well. Only 3 adult Lygus were found this time with numerous big–eyed bugs indicating the big–eyed bugs are efficiently eliminating the other life stages of Lygus. Other beneficials found were six–spotted thrips and several spiders. Ants were also present. Their presence will make the control of whiteflies and aphids more difficult as they will protect these pests as food sources.

Farms being sprayed in the area&

Currently there are no significant numbers of pests (boll worms, Lygus, aphids and spider mites) in this field. In contrast, a cotton field off I–5 with apparent mite damage was being sprayed the morning we drove to Bakersfield.

Some weeds help biological control:

The weeds in the corn and the watermelons add to the habitat diversity by providing alternate sources of prey for generalist predators such as lacewing, minute pirate bugs and big–eyed bugs. These weeds allow tremendous populations of these generalist predators to build up which will easily suppress pests such as aphids, thrips and Lygus preventing damage to the cotton. This field is an excellent example of how just slight changes on farming practices that include managing weeds as part of a sustainable agriculture farmscaping scenario creates a better and more preventive pest management system by increasing both the number and diversity of beneficial insects relative to pest insects. Of particular importance is the staggered planting of corn. This staggered planting of corn will always have a stage that is more attractive than cotton for corn ear worm and will provide a continual source of pollen that will extend the longevity and the fecundity of the beneficials (Trichogramma and lacewing) already released. Many praying mantis and some Polistes wasps were observed while walking through the field.

Releases:

The corn earworm (a.k.a. cotton bollworm) has done some damage in the sweet corn crop, but the weekly releases of Trichogramma should develop into a large enough population that later generations will prevent a future outbreak of this pest protecting the later stages of corn and cotton.

 

Reynolds – July 12 & 13, 2001

South Lake Rd, Chevron field

Sweep net samples:

Only the north end of the field was sampled as the rest was being irrigated.

1 flower fly (=Syrphid)

1 Tachinid fly

several types of tiny wasps (probably parasitic)

1 Assassin bug (Zelus spp.) egg mass

1 Damsel bug adult (=Nabid)

1 Trichogramma

many Big–eyed bugs (=Geocoris)

many lady beetle

1 lacewing adult

D–sVac analysis from 50 plants:

The beneficial insects are far more numerous than the pests. Only 3 large Lygus nymphs were found compared to ~100 big–eyed bug nymphs. Some whiteflies were found but should held in check by the generalist predators. Also ~10 1 day old loopers will also be eaten before they reach the larger stages. There were many spiders, lady beetles, Tachinid flies, assassin bug nymphs, and hooded beetles.

Because this field was under irrigation, only the north side of the field was sampled with the sweep net and D–Vac. The cotton is virtually pest free as confirmed by our sampling and the foreman’s observations. The uneven plant growth in this field is most probably due to uneven irrigation. We would like the foreman who does most of the walking though the field to be more involved with relaying information to his coworkers. The more eyes that understand the processes they are seeing the better the natural control of pests will be. In the areas where we could sample a tremendous number of lady beetles and lacewings were seen. These beneficial insects may have migrated from the harvested wheat and hay fields surrounding this field. Several hover flies (Syrphids and Tachinid) spiders, the dragonflies, and damselflies, the praying mantis and a large black ground beetle, Calosoma affinae were seen on the western side of the field. These insects represent only a few of the most conspicuous predatory forms occurring in the cotton arthropod complex.

Habitat plantings would be helpful:

Even though this field is surrounded by extensive wild areas with native shrubs, planting a hedgerow like the one at Sanders would enhance the biological control late season pests (particularly aphids and whiteflies) when the surrounding area is completely dried out. During the cottongrowing season, the activity of natural enemies is affected by local physical environmental conditions, mainly lack of water and high temperatures. An irrigated planting provides a place where natural enemies can continue to flourish. Also parasites live longer and destroy more pests when there are some weeds or other plants to provide pollen, nectar and shelter. Strip or trap cover crops that are never sprayed offer a field insectary and winter refuge for beneficial insects. Sunflower and sorghum borders are particularly good habitats for growing lacewings and other natural enemies on the farm. Corn and alfalfa borders and interpolating of flowering plants can also increase Trichogramma parasitism of moth eggs in the crop.

 

Sanders – July 12 & 13, 2001

South Lake Rd, field 24E

Plant growth:

Plants are somewhat small but support tremendous amount of flowers. Hopefully the plants will have enough nutrient resources to retain a high percentage of resulting bolls.

Sweep net samples:

East and west sides of field sampled the length of field.

12 Big–eyed bugs (=Geocoris)

3 Spiders

4 Damsel bugs (=Nabis)

4 Lady beetle

2 Lacewing

2 Minute pirate bugs (=Orius)

D–Vac analysis from 50 plants:

A tremendous diversity of insects (mostly beneficial) were found here because of the diverse habitats (alfalfa, hedgerow plantings and uncultivated fields) surrounding this field. All life stages of big–eyed bug were present with a single Lygus adult indicating the immature Lygus are being eliminated by numerous predators. Some of the generalist predators found were crab spiders, Collops beetles (predator of stink bug eggs), assassin bug eggs, many hooded beetles, 6 spotted thrips, 2 species of lady beetles, Apanteles marginventralis, and a Gymonsoma, a parasite of adult stinkbugs. This type of biodiversity is only possible because habitats support so many different alternative prey for the generalist predators and parasites. Several whiteflies were also found. Hopefully the abundance of predators and the releases of Eretmocerus will keep these pests in check. There also are abundant numbers of Nabis, Geocoris, Orius, Ladybeetles, and various beneficial hover fly sp.

Habitat Hedge:

The habitat planting has developed as a refuge for beneficial insects. Last week we weeded the hedge by hand again. The plants are developing very well, but the addition of organic mulch (50–100 lbs. total) around each plant would suppress the weeds, conserve water by reducing evaporation and promote plant growth by providing nutrients as the mulch breaks down and by reducing nutrient competition with weeds. When the habitat was first planted in June, the drip irrigation was on for several consecutive days. Now that the plants are more established, the water has been restricted for just few hours a week. We have been talking to the foreman and other employees about this refuge in order to get help to maintain the irrigation lines.

Effects of different beneficial habitats:

During the cotton–growing season the activity of some of these natural enemies can be affected by local physical environmental conditions. Also parasites live longer and destroy more pests when there are weeds or other plants to provide pollen, nectar and refuge. Several dragonflies and damselflies (both voracious general predators) were seen flying around, as well as some Hypososter pupae and Polistes wasps. Also noted were lacewing eggs and egg masses of Zelus at different locations. Harvesting the adjacent alfalfa field a few weeks ago could have prompted moths to fly into the cotton, but they are few and no large worms were seen in the sweep net samples or on the plants.

Releases:

Lacewing and Trichogramma were released throughout field. Eretmocerus, a parasite of silverleaf whitefly, was released in the cotton near the habitat planting for two reasons: (1) the habitat is available to support the parasites, and (2) a few whitefly were seen on cotton leaves.

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