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corn earworm

All Crops    Treasure Valley - Idaho

Posted on: July 16, 2008 by Jerry Neufeld

BELOW ARE PDF FILES WITH THE RECOMENDATIONS FROM THE 2008 PNW INSECT MANAGEMENT HANDBOOK FOR CONTROLLING CORN EARWORM LARVAE IN SWEET CORN SEED, AND FIELD AND SILAGE CORN.

» Control for earworm in field and silage corn

» Control for earworm in sweet corn seed-1

» Control for earworm in sweet corn seed-2

corn earworm

Corn    Treasure Valley - Idaho

Posted on: July 16, 2008 by Jerry Neufeld

The University of Idaho CIS 366 entitled “Timing Corn Earworm Control,”states that summer moths will begin laying eggs in fresh corn silk at approximately 1300 growing degree days (GDD). Egg hatch and larvae attack will begin about 73 GDD later.

According to the Oregon State University GDD model for Corn Earworm (http://pnwpest.org), we are currently at 978 GDD in the Caldwell area, 927 GDD in the Nampa area and 1126 GDD in the Parma area. We are accumulating approximately 20 GDD per day. We will hit 1300 GDD in the Caldwell area on approximately 8/1, in the Nampa area we will hit 1300 GDD on approximately 8/2, and in the Parma area we will hit 1300 on approximately 7/23. Those fields with fresh silk at 1300 GDD are most vulnerable to attack from corn earworm larvae. We will hit 1300 GDD about 7-10 days later than last year.

The following information was taken from CIS 366 regarding corn earworm.

Corn can be “scouted” for corn earworm eggs to predict possible infestation levels. Examine 10 silk masses (about 2-day old) on each edge of a field but only in those fields which are beginning to silk or are silking. Examining a field in late silk for the first time is worthless; most of the eggs, if any were present, are already hatched, and the damage cannot be prevented.

When the egg counts average 1 egg per 2 silk masses, about 100% ear infestation will occur in the field and other fields of like maturity in the vicinity. With 1 egg per 2 silk masses, about 1 inch of each ear tip will be damaged; 1 egg per silk mass will result in about 2 inches of the ear tip damage, etc. When the days and nights are warmer than usual, the damage may double because the earworm will develop faster than the corn.

Fields should be scouted about every 2 to 4 days, depending on temperatures. Once economic egg levels are reached, determined on the basis of damage expected, further scouting is unnecessary. All fields which silk after that time in that vicinity will be subject to damage.

No chemical control will control worms in the ears, so sprays must be timed to control the larvae on the silk before the worms enter the ears. Make the first application when the plants are 50 percent silk, and repeat in 5 to 7 days or as necessary.

» Corn Earworm Egg

» Corn Earworm Larvae

powdery mildew in sugarbeets

Sugarbeets    All Locations

Posted on: June 27, 2008 by Jerry Neufeld

The Amalgamated Sugar Company Field Representatives are saying that now is the time to plan your treatments for powdery mildew in sugarbeets. While mildew has not yet been found in the Treasure Valley, White Satin Field staff say the modes of action of the mildew chemistries work best if treatments are applied before mildew is found in the field. They are recommending mildew applications in the west end of the Treasure Valley the week after July 4 regardless of whether or not your fields are surface or sprinkler irrigated. You may also want to include an insecticide treatment for black bean aphid or loopers in the mildew tank mix. CONTACT YOUR WHITE SATIN FIELD REPRESENTATIVE FOR INFORMATION REGARDING THESE TREATMENT RECOMMENDATIONS AND ROTATION OF CHEMISTRIES.

Western Cherry Fruit Fly

Tree Fruits    Treasure Valley - Idaho

Posted on: June 12, 2008 by Jerry Neufeld

Ben Simko from ISDA has prepared a memo with the recommended first treatment dates for Western Cherry Fruit Fly for several areas in the Treasure Valley. To see the memo click on “Crop Info” then “Tree Fruit” then “Cherry” then “Western Cherry Fruit Fly” then click on the link entitled “Western Cherry Fruit Fly Predicted Emergence for 2008.” For treatment information scroll down to the Western Cherry Fruit Fly Alert Tony McCammon posted on June 3, 2008.

» Western Cherry Fruit Fly

Late blight forecast

Potato    All Locations

Posted on: June 10, 2008 by Jeff Miller

The late blight forecast for the 2008 growing season in southern Idaho is negative. Even though we have been experiencing cool, wet weather recently, the amount of precipitation has still been relatively low compared to previous late blight years.

Additionally, temperatures have been outside the favorable range for pathogen development.

This forecast is only an estimate of the threat of late blight. It is still critical to scout fields for the presence of late blight as the canopy develops. Late blight is likely to be found first in the center span of pivots, in irrigation overlaps, field areas with sub moisture, along mainlines, or in shaded areas where periods of leaf wetness are extended.

If you find any suspicious lesions, please send them to University of Idaho personnel for confirmation.

Colorado Potato Beetle

Potato    Treasure Valley - Idaho

Posted on: June 9, 2008 by Jerry Neufeld

Dr. Mike Thornton, from the UI Parma Research and Extension Center is reporting that overwintering Colorado Potato Beetle adults are beginning to emerge. This overwintering adult stage does not do any damage, however, they are looking for mates. In the next few days females will begin laying eggs in potato fields. We could see the damaging larvae appear in about 7 to 10 days depending on temperatures. Growers should be watching for the egg hatch to time a foliar spray for the first generation of CPB larvae.

» CPB Eggs

» CPB Larvae

» CPB Adult

Western Cherry Fruit Fly Alert

Tree Fruits    Treasure Valley - Idaho

Posted on: June 3, 2008 by Tony McCammon

Western cherry fruit fly is a serious pest of tart and sweet cherries. Although residential growers can “tolerate” several wormy cherries, please keep in mind that a commercial growers’ crop can be rejected by the processing plant if worms are detected. If residential trees are adjacent to commercial orchards, it is essential that they are treated for cherry fruit fly.

The timing of your spray depends on the development of the fruit. We usually recommend starting applications at 1060 degree days after March 1. However, the flies cannot penetrate the skin of the cherry to lay eggs until the cherry has developed a salmon-blush color. So use that guideline for when to start spraying. Check the fruits at the top of the tree and in the sunniest locations as these will color up first.

Currently in the warmest sites in the Treasure Valley we are at 880 DD in cooler sites we are 820 DD in either case the Valley Growers should be preparing to spray next week.

Once control treatments begin based on timing information described above, maintain protection of fruit through harvest. Reapply insecticides based on the protection interval stated on the label. It is best to rotate the type of insecticide applied between applications to reduce development of resistance and negative effects on beneficial insects and mites. For example, insecticides such as carbaryl, malathion, and the synthetic pyrethroids are especially toxic to predatory mites.

Recommended Insecticides*
For home and commercial orchards:
• spinosad (GF-120, Success, Entrust) – reapply every 7 days
• carbaryl (Sevin) – reapply every 7 days
• malathion (Malathion) – best when used just before harvest as it lasts approximately 3 days
• synthetic pyrethroid insecticides – reapply every 7-14 days
• cyfluthrin (Baythroid) – commercial use only
• esfenvalerate (Asana, Ortho products)
• lambda-cyhalothrin (Warrior) – commercial use only
• permethrin (Ambush, Pounce, Ortho products)

For commercial orchards only:
• imidacloprid (Provado) – reapply every 14 days
• azinphosmethyl (Guthion) – reapply every 14 days (scheduled for phase-out by 2012 by the U.S. Environmental Protection Agency)
• phosmet (Imidan) – reapply every 14 days; do not use on sweet cherry
• chlorpyrifos (Lorsban) – reapply every 14 days; do not use on sweet cherry
• diazinon (Diazinon) – reapply every 10-14 days
• spinetoram (Delegate) – Reapply every 7 days

Spinosad, GF-120 is used by many growers across the country with great success (in Washington, they use this product almost exclusively). If you have a heavy infestation, it will take 1-2 seasons of use to bring 100% control with this product. It contains a bait that attracts the fly to eat it, and the active ingredient is called spinosad. Spinosad is a metabolite from the naturally occurring soil bacterium, Saccharopolyspora spinosa. GF-120 must be applied every 7 days, but complete coverage is not necessary.

Ground Cover and Mulches
It has been demonstrated that ground cover around the base of trees can prevent larvae from burrowing into the soil to complete development into the pupal stage. Successful vegetation covers include grasses and other plants with extensive, dense root systems (e.g., clover) that physically impede fruit fly larvae. Landscape fabric has been shown to prevent larval burrowing and emergence of adults from pupae in the soil. Mulches of other dense materials may also interfere with their life cycle.

Codling Moth Update

Tree Fruits    Treasure Valley - Idaho

Posted on: June 3, 2008 by Tony McCammon

Codling Moth
Cooler weather in my experience has created less of a gap between first and second generations Moth pressure will remain constant through this cooler spell. Trap catches of codling moth adults have declined due to the combination of cover sprays and the weather induced waning moth flight. However, we have entered the peak period of egg hatch (340-640 DD after biofix) where it is very important to have the fruit protected. This is the time where you might consider overlapping with your first cover spray.

Some new research out of Washington State University by Jay Brunner and others discusses tank mixing two different types of materials: one that acts as an ovicide (Rimon, Esteem) with one that acts as a larvicide (Assail, Calypso) as an alternative to the organophosphates. This combination provides a one-two punch of killing existing and future eggs (depending on residual time) and existing and future larvae (whose eggs had not been killed).

Otherwise stick to your guns and continue your regimes. Current DD for your areas are below:
Caldwell: 462.8
Parma: 357.8
Fruitland: 374.8
Payette: 337.4
Emmett: 321.2