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(BASIC) June 28 & 29 Report
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For All Growers: Trip Report June 28 & 29, 2001

Kern County BASIC Pilot Program

Deke and Francisco Cornejo made and compiled the report.

 

Loopers under biological control:

In general beneficial populations are growing as indicated by the abundance of eggs and immature stages of several generalist predators. The looper populations are being held in check by several predators (hooded beetles, birds, big–eyed bugs, Orius, lacewing and lady beetles) and parasites (Hyposoter, Apanteles, and Voria wasps and Tachinid flies). Fewer small larvae were found this week compared to last week indicating that the beneficials are causing the reduction. By looking at not only the ratio of beneficials to pests in a sample but the life stages present in a sample, a better assessment of impact of the beneficials can be made. In this case because the beneficial populations are reproducing and the loopers are not, the loopers are under control even though their populations are high.

Leaving some weeds helps grow beneficials

The best balance of beneficials to pests was found in samples taken from the South Lake Rd locations (Sanders and Reynolds). This is due to the greater diversity of surrounding plantscape in this area. Most of this plantscape consists of a variety of weeds. These weeds are very important because they have a wide variety of insects feeding on them and indirectly support an even greater variety of beneficials that feed on plant eating pests. In contrast, the other sites have hardly any diversity in the surrounding plantscape due to vigorous weed control efforts. By limiting the weeds, the diversity beneficials is also limited. This limitation can be overcome if the surrounding plantscape is managed actively by planting beneficial insect habitat. The more diverse the plantscape the more consistently pests can be managed biologically.

 

Francisco’s Field Report June 28–29

 

Antongiovanni – E. Bakersfiel

Field observations:

This field was sampled just before sunset on Thursday. Several birds were flying from the interior of the field. Hyposoter pupae were found at several locations. In general the crop is very clean at this point. The only worry is the adjacent safflower field is almost ready to be harvested and may cause a large migration of Lygus when it is harvested.

Plant growth:

Petiole samples were collected Friday morning. Plant growth in this field is very homogeneous. Plants in some areas are at different growth stages but these differences may be due to different soil zones. The petiole sample analysis will reflect the average on the whole field. High nitrogen input increases the risk of mite and aphids outbreaks as these pests thrive on tender plant growth induced by fertilizer use.

Sweep net samples:

Sweep net and D–Vac samples were taken from the four corners of the field.

5 Geocoris

1 Orius

3 Nabis

6 Ladybeetles

6 lacewings

3 Spider

2 Hyposoter

D–Vac analysis:

High numbers of thrips, hooded beetles (several species of Anthicids), and minute pirate bug (Orius) were found. The high thrips population is the food source maintaining the minute pirate bug population. The hooded beetles are feeding on looper eggs and larvae. More immature stages of beneficials compared to pests were found indicating these pests will be kept under biological control.

Habitat:

Few of the corn seeds that we planted few weeks ago are beginning to sprout. The disappointing growth of the corn may be due to residual herbicide use.

Releases:

100,000 Trichogramma were released through the center of the field. As a proactive measure, lacewing releases should be made next week to reduce the risk of a mite and/or aphid out break. Also these releases would increase the general predation on stinkbug and Lygus eggs and nymphs. The farm manager agrees and would like his people to be involved with the releases so that they learn more about the program.

 

Francisco’s Field Report June 28–29

 

Banducci – W. Bakersfield off Buena Vista Rd.

Sweep net samples:

Samples were taken from the westside of the farm away from the beehives

4 Geocoris

2 Nabids

5 Ladybeetles

2 Lacewings

3 Lygus

D–Vac analysis:

The corn is providing a source of food for thrips which in turn is a food source for the minute pirate bug which was numerous in this sample. Other generalist found were lacewings and big–eyed bugs

Decision to not spray:

This farmer had to spray his sweet corn with Javelin (a soft Bt pesticide) to reduce the number of Heliothis zea he found there. We talked at his produce stand where he showed me the damage done by the worms. We talked about how our Trichogramma releases should limit the damage caused by the next generation of Heleothis zea but some damage on the corn was to be expected. Javelin is the most compatible pesticide to control the damage to the corn without disrupting the effect of the Trichogramma releases.

Releases will continue to be made in both the corn and the cotton when needed. This grower is already harvesting sweet corn so there is plenty of pollen to support lacewings so I believe that we could start making some releases this week. Due to his irrigation schedule the Trichogramma releases were made only at the western side of the cotton field and in the sweet corn. The placement of several beehives near the Chinese berry tree will make it more difficult to sample and release in this area.

 

Francisco’s Field Report June 28–29

 

DeStefani – W. Bakersfield off Green Rd

Plant growth:

In general this farm is doing very well. The cotton plants are very well developed, taller and with a deep green lush foliage.

Sweep net samples:

Samples were only taken on the East side of the field because 75% of the field was under irrigation. The results are:

6 Geocoris

2 Nabis

2 Orius

3 Lady beetle

4 Lacewings

2 spiders

3 nymph lygus

7 Hyposoter (a worm parasite) pupae

D–Vac analysis:

Many reproductive stages of general predators were found but few small looper larvae. Few stinkbugs and lygus were also found. These pests are low in number and serve as a food source for the general predators. Also, several worm parasites were found; Hyposoter and Apanteles attack small loopers, Voria wasps attack large worms, Tachinid flies attack several stages. Both the parasites and the predators were responsible for reducing the looper population.

Decision to not spray:

I believe that I observed a bio–control phenomenon this week in this field. Last week Deke and I reported we found high numbers of loopers larvae here which made us anxious about what we’d see this week. I spoke with Jose, the foreman, about the number of worms. He thought he would have to recommend spraying the field to reduce the number of worms. I checked this field twice on Thursday (mid–day and again at 5pm) because it was difficult to find any looper larvae. I took a second D–Vac sample the following morning.(June 29) very few worms. Even though the field had just been irrigated, Jose (the Foreman) and I walked through and checked more plants for loopers but found very few.

Analysis of the biocontrol:

I wondered what had happened to the worms that I saw last week. I noticed high numbers of blackbirds around the field. Also, last week’s samples had many Hyposoter a common parasite of worms. This parasite can parasitize up to 60% the larvae present in a field. It is very likely the combination blackbird predation and parasitization by Hyposoter (the Hyposoter pupae found in the sweep net samples) were responsible for reducing the number of loopers during the past week. More importantly the necessary combination of predators and parasites have been primed to control the next invasion of worm pests, the cotton bollworm Heliothis zea. These observations illustrate how biological control can pleasantly surprise us. Biological control doesn’t rely on a single parasite or predator to control a pest, but rather it depends on the combination of several predators and parasites to reduce pest numbers. Science cannot predict which combination will provide the best control which is why it is so very important to provide diverse habitat to support as many parasites and predators as possible.

 

Francisco’s Field Report June 28–29

 

Reynolds – South Lake Rd, Chevron field

Field observations:

No mites or aphids were seen on the plants or in the D–Vac samples taken from the field edges. Many ladybeetles flew around when the plants were disturbed. The high populations of beneficials are being supported by the surrounding open fields. The sprinkler was working very well last week but some areas of the field appear not to be getting enough water as indicated by the smaller plants. In general this field is clean without weeds or pests.

Plant growth:

Plant sizes here are more variable than elsewhere. The causes may be reflected in the petiole samples taken this week. The plants look very healthy with deep green foliage.

Sweep net sample:

6 Geocoris

2 Orius

5 Nabis

7 Ladybeetle

Lacewings

3 Spider

D–Vac analysis:

A very favorable balance of beneficials to pests was found thanks to the diverse surrounding plantscape. This field is as clean with the number of beneficials far exceeding the number of pests.

Releases:

100,000 Trichogramma were released through the center of this field.

 

Francisco’s Field Report June 28–29

 

Sanders – South Lake Rd, field 24E

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 Orius

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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