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(BASIC) July 5 & 6 Report
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For All Growers: Trip Report July 5 & 6, 2001

Kern County BASIC Pilot Program

Deke and Francisco Cornejo made and compiled the report.

 

Antongiovanni – July 5, 2001

Field observations:

Half of the field has been too wet to walk, both this week and last week. So we sampled only the south half this week. The pest insects are under satisfactory biological control. Lygus populations have remained well below any economic damage thresholds since our first visits. We are monitoring the insect populations weekly. There have been no insect pest threats and there is a continual decline of loopers this week. The moth flight is over for this generation.

Plant growth:

We took some petiole samples. We are waiting for the report because we observed much worse plant leaf chlorosis. We are concerned about the increase of chlorosis throughout the field, but in particular where the soil is most sandy at the east end. The new growth at the tips of the plants is green, so the plant has adjusted itself. We are asking the question about possible effects from herbicides that might have moved in the soil during the irrigation just completed.

Releases

We walk through the rows of the field colonizing beneficial insects each week. Trichogramma and green lacewing larvae are parasitic and predatory on cotton worms (loopers and bollworm).

 

Banducci – July 5, 2001

Field observations:

The ratio of good bugs to potential pest species is very favorable for biological control. The alfalfa hay to the south was harvested last week and is irrigated and growing rapidly again with fewer worms and lygus than before. The biodiversity of the natural enemy complex is more visible in this cotton block, due to a slightly higher density of pests, particularly the cotton leaf worms, Trichoplusia ni and alfalfa looper, Autographa californica. Honey bees for pollination are placed near the trees making this block favorable to biological control. Bt is the choice for spraying the worms in the corn. One application has been made.

Pes:beneficial ratio:

Besides the few loopers, lygus, spider mites, cotton aphids are very light or not found. Therefore, the main food source for the predators are the few small worms and eggs of loopers. Western flower thrips are prey for black hunter thrips, minute pirate bugs and hooded beetles. The few lygus and occasional stinkbug are preyed upon by big–eyed bugs and damsel bugs. The "good bug/bad bug ratio" can be favorable to biological control at very low total insect population densities as well as slightly higher population densities. The sampling of 40 plants is arbitrary. The favorable ratio is the key to predicting future progress of biological control processes.

D–Vac sample:

Where there are small insect prey, even the cotton fleahopper is more of a predator than a plant feeder. Potato leafhoppers and Aceratogallia leafhoppers are alternate prey for big–eyed bugs when lygus populations are at this low density. Several Tachinid flies, such as Voria ruralis, adults and puparia are seen on the loopers. We found one Celery leaftier adult and many green lacewing adults particularly in the sweet corn. Eggs and larvae of green lacewing are becoming more common. There are many spiders feeding on these insects. fungus gnats or midges are another harmless food source for predators. Western fire ant is common in the alcohol samples.

Habitat:

There are more kinds of plants due to the few weeds, the five staggered plantings of sweet corn and the watermelons and two alfalfa hay fields that appear to be untreated and are alternately harvested adjacent to the cotton. Corn earworm (=cotton bollworm) is attracted to corn and not to cotton at this time.

Releases:

Trichogramma and lacewings were released.

 

DeStefani – July 5, 2001
Field Observations:

Ants are along the road between alfalfa and cotton on the south side and the west end by irrigation cemented ditches. The ratio of beneficials to pests is favorable and the worms are gone.

D–Vac sample:

The cotton aphid was low with low levels of ladybugs (Scymnus sp.). Also low levels of predatory midges and lacewing. Whitefly were low and mainly controlled by Geocoris punctipes that was reproducing. Lygus were low, mostly nymphs, and being eaten by medium populations of Geocoris and low levels of damsel bugs, and various spiders. The Says Stinkbug was present at low level with signs of predators and the egg parasite. The cabbage looper is accompanied by Apanteles and Hyposoter wasps, Copidosoma and Prospaltella. Voria ruralis, the Tachinid fly, was present. Eating low levels of spider mites are low levels of predatory midges on mites and black hunter thrips. Minute pirate bug is common feeding on low levels of Western flower thrips. Besides Western fire ant, other pests in the samples were leafhoppers, bluegreen sharpshooter and Empoasca and other natural enemies were the red mirid, Chloropid flies, Psocids, Colembola and Drosophila.

 

Bob Reynolds – Thursday, July 5 & 6, 2001.

22520 Copus Rd., Bakersfield, CA 93391. Pima cotton block west of Sanders – Lake bottom, Maricopa area.

Field observations:

This cotton block has had very favorable numbers of natural enemies and very few potential cotton pest species in all of our monitoring using the standard sweep nets, visual examination of plant parts and the D–Vac vacuum insect samples from 40 plants taken in four locations. The standard sweep net and visual plant counts are recorded, while the insects that are vacuumed are placed in ethyl alcohol, examined with a microscope and kept stored for future reference as a permanent record of the progress by date of the biological control organisms in this field.

Sweep net samples:

The only potential pest insect coming from the wheat is the Says stinkbug Chlorochroa sayi. A beetle Collops vitatus is a predator on stinkbug eggs in both wheat and cotton and a wasp Trissolcus sp. is a parasite on the eggs. Both are present. Lygus populations are very low and no eggs or nymphs are seen. three species of big–eyed bugs Geocoris pallens, G punctipes and G atricolor (brown, grey and black in color) are the best predators of lygus and other leafhoppers, particularly the eggs and small nymphs. Some plant destruction occurred on seedling cotton plants from a small mammal, possibly rabbits, requiring replanting around the edges of the field.

There is a favorable ratio of good bugs. The presence of beneficial insects indicates very low populations of their prey and therefore, a very favorable sign to good progress in biological control. The biodiversity of the natural enemies is extensive in this field of cotton at this time.

Plantscape:

Around the farm there is much diversity and wildness and no pesticide interference from drift effects. The wild sunflowers host sunflower aphids and possibly whitefly and provide nectar and pollen. Lacewings are attracted to such plants. The wheat field west of the cotton matured and was harvested in time for the insects from the wheat field to migrate to the adjacent cotton planting.

D–Vac samples:

There have been only a very few winged cotton aphids and no mites or whitefly seen in our samples. there are many ladybugs: the Julian ladybug, Coccinella perplexa var. juliana, the variable ladybird beetle Exochomus marginipennis and Hippodamia convergens adults that migrated to the cotton. Flower tghrips are prey for hooded beetles Notoxis constrictus. Large numbers of these Anthicid beetle adults moved into the cotton suppressing thrips to very low numbers. Minute pirate bugs Orius spp. also live on thrips, spider mites and leaf–eating looper moth eggs and small larvae. No mites and few cotton worms are found.

Rodger & Sandy Sanders – Thursday, July 5 & 6, 2001

OLD RIVER FARMS – Lake bottom, Pima cotton

Field Observations:

There is a satisfactory ratio of good bugs with this being the most diverse set of plant and insect biodiversity. Since no herbicides are used and there are a few weed species, they diversity the farm further. The presence of many reproducing predators with few pest adults is a very favorable sign for progressive growth of the natural enemy complex that must increase to be ready to suppress any sudden migration of pests from outside the plantscape as the cotton plants advance their growth cycle to maturity. Tachinid flies are difficult to sample and identify as adults, but they are seen as we walk the fields colonizing the insectary grown parasites. One very colorful black and yellow tachinid Gymnosoma fuliginosa parasite of adult Chlorochroa sayi stinkbug was observed in the alfalfa at the last cutting. There is even a pair of insectivorous toads living in this field of cotton, good proof of the lack of any pesticide residues.

The cotton field samples show a steady growth of plant size that has a favorable balance of light populations of plant feeding insects that in turn are food for the larger numbers of natural enemies of the pests. There is an absence of immature half–grown pests and the presence of all life stages of predatory species. This means that predators are eating their prey as fast as the immature pest individuals emerge from their eggs.

D–Vac sample:

We find a very few whitefly adults. The level of insect life supports larger populations of many species of spiders, particularly crab spiders that are known to capture adult lygus. Adult lacewings are more common here because of the alfalfa and the blossoms and pollen in the permanent hedge and Insect–a–Flora Mix along with the corn tassels. Minute pirate bugs, hooded beetles that feed on thrips and spider mites, six–spotted thrips (predators of spider mites), Julian and convergent ladybugs, damsel bugs, assassin bugs Zelus renardii, Western fire ants are all common in the samples.

The D–Vac vacuum insect net samples immature insects much more efficiently than the sweep nets. The numbers of eggs and one and two day old immatures is much greater than an adult census. The few adult lygus that lay eggs are controlled every day by these predators of lygus, particularly the big–eyed bugs. The vacuum insect samples show the correlation of predators and parasites to their prey. The samples show that the natural enemies are killing the lygus nymphs before they hurt the cotton and the few adults eventually die of old age or must be eaten by spiders and birds.

Alfalfa cutting was innovative way to conserve natural enemies:

The alfalfa hay is an asset for maintaining the full natural enemy complex that is known to support biological control of cotton pests. Sander’s management of the hay harvest for the second cutting was unique. Seven borders of uncut hay were left standing distributed from the midpoint of the field to the end away from the cotton (north end). Thus, the adult insects followed the mowing process as it moved away from the cotton block. We happened to be able to take vacuum samples that showed that the plantfeeding insects, particularly the lygus adults, concentrated in these seven strips of hay that were left standing. This attracted particularly the lygus and stinkbugs to lay eggs which were immediately attacked by the high numbers of predators that had moved with the lygus: Big–eyed bugs, Anthicids, damsel bugs, Collops beetles, stinkbug egg parasites, and more. There were a large number of eggs of these predators remaining in the borders when all of the remaining hay was cut a few days later. Thus, all of the hay was harvested without sacrificing any to habitat trapping. The adult insects dispersed into the cotton east of the alfalfa, but the immature predators that have no wings were forced to clean up the stubble left from delayed cutting of the border strips.

The overall effect of this harvest process was very favorable to biological control. The next alfalfa harvest will be even more critical for trapping lygus in the alfalfa. George Long, the foreman, plans to leave a border of uncut alfalfa standing along the south and east border of the hay field that will continue to attract (trap) the lygus while going to seed. We will be monitoring this harvest process.

The key is to not cut all the hay at once:

Fortunately, biological control processes are flexible and since they are driven by food supply, there are more than several ways to manage the alfalfa harvest to keep the natural enemy complex working. The only way that we know that does not work well is to cut all of the hay at once leaving the insects in the stubble in the hot sun. The insects seek shade and food in the cotton and too many will enter the cotton suddenly sending more lygus into the cotton too far ahead of the predators that chase after them. The uncut border of alfalfa should work to keep most of the lygus out of the cotton until the hay starts to grow again when they will return to the alfalfa plants. Lygus prefer growing alfalfa hay to cotton!

The Hedge against Whitefly is feeding natural enemies:

Alongside the perennial habitat planting for sustainable biocontrol of whitefly we have a dust barrier of Sudan grass plus annual insectary mix of seeds to enhance natural enemies. Corn plantings to trap corn earworm (=cotton bollworm) also enhance green lacewing populations. Alyssum is in full bloom to feed natural enemies.

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