February 2004

I’ve cut quite a few stone fruit buds in Mesa and Delta counties the last several weeks. The early January temps for most of the industry was in the neighborhood of –4 to –5. There were a few spots that hit the -8 to –10 mark. That 4 to 5 degrees had a considerable impact. In most orchards you can find a dead bud here and there, natural mortality. In the area’s that were 4 to 5 degrees colder there is a different story to be told. The damage is far more evident with some varieties surviving better than others.

After a number of years we’re finally having a real winter with a few mornings in the “belows” and lots in the single digits. Suppose we can put the sprayers away this year since all the pests have froze to death? What is the impact on pest populations from low temps? Each year there’s a certain percentage (high or low) of winter mortality. Air drainage, snow cover, micro-habitat, genetic characteristics of local populations, and simple raw temps all impact the survival of pests. Let’s say for discussion’s sake you’re down to a handful of individuals left in your orchard. Forget what lies behind and focus on the future! The greatest factor on the coming season’s pest populations is the early spring conditions we encounter. Favorable development weather early in the season can easily compensate for a small over-wintering population. Conversely, a cold, wet and extended spring can be as effective as a well-timed early season spray program towards reducing populations. The growth of most pre-bloom arthropod populations is pretty much determined for the first half of the season by early spring weather patterns. Mites, aphids, plant bugs and lygus are obvious examples that suffer from cold, wet, rainy and windy springs. But, bring on a hot, dry and quick spring and watch what happens!

As long as spring conditions are on the focus…..I know I said this last year, but it’s worth repeating. Pay attention to the spring weather in regards to Fireblight and Coryneum blight. They both depend on temps, moisture and the pathogen. Hopefully the pathogen “source” has been reduced to a minimum through good sanitation and spray programs. That leaves the weather. For fireblight conditions pay close attention to WSU’s model “Cougarblight” found on the web at www.ncw.wsu.edu/treefrt.htm . Coryneum blight, has an infection period that also depends on temperature and moisture. With 24 hours of continuous moisture and temps above 36°F an infection can occur. Warm the days up to 77°F and Coryneum can start up with 6 hours of moisture.

There’s a number of new materials or label changes for existing products this season. The remainder of this letter deals with ones that could be important to you.

Calypso – A new insecticide from Bayer. A chloronicotinyl in the same family as Actara, Assail and Provado. Calypso is labeled on apple and pear for aphids, OFM and Codling Moth.

Chateau – A new broad spectrum broadleaf and grass residual herbicide from Valent. Registration is expected this season for grapes, non-bearing fruits and non-crop areas. Valent expects full registration for bearing fruits in 2005. This material is extremely safe on young trees and vines! It is non-volatile and relatively insoluble with minimal leaching potential. Incorporation through moisture (1/4”) is necessary to activate Chateau. The material doesn’t break down from UV (sunlight) degradation so it can sit on the soil surface for an extended length before incorporation.

GF120NF – A new insecticide bait from Dow. This is a new formulation of Spinosad. The target that this will work well for is western cherry fruit fly. What makes this of interest is that it can be applied at very low volume and high speed. Research shows that nozzles on the back of an ATV moving at 10mph squirting a stream into the tops of the canopy worked amazingly well.

Metalosate - Albion Labs has submitted all the paperwork required for organic certification and is waiting to hear back on it’s new line of powdered foliar nutrients.

Provado – Bayer greatly expanded the label for this product with one very important addition! It’s now labeled for stone fruit!!! Apricot, nectarine and peach have been added. We now have a great choice to clean up aphid problems in peaches.

Nexter – A new miticide from BASF. Labeled on Grapes. Peaches, Plums, Prunes and Nectarines.

Pristine – A new fungicide from BASF. Labeled for Grapes, Stone fruit and Cherries. Pristine is a combination of two active ingredients that give it the ability to control the disease at two points within it’s reproductive chain. The addition of this material will give you another tool for rotaton against disease resistance.

Carpovirusine – (Granulosis) During the 2002 season granulosis virus was sold in Colorado under the Virosoft label. Unfortunately this product out of Eastern Canada was literally a dead product. The active ingredient was killed during the manufacturing process. There was quite a bit of dissatisfaction (rightly so) over the results. We have to be careful to not throw the baby out with the bath-water! Granulosis virus is a viable and useful tool for codling moth control! Sumitomo Corp. has re-introduced granulosis under the trade name of Carpovirusine. There were a number of independent research reports presented at the Portland entomology meetings that were all very positive. We tried Carpovirusine last year (2003) on a limited basis. A bit of background info on granulosis:

First isolated in Mexico in 1964.
In 2003 an estimated 12,000 acres had an application in the US. In Europe 200,000 acres.

The active ingredient is a granule and less than ½ a micron in size.

It’s a protein that must be ingested.
The LD/50 has been determined to be less than 2 virus granules/larva.

Following ingestion the granule is dissolved in the alkaline pH of the gut. Virus replication takes place within 48 hours following infection. Symptoms of the disease develop slowly. There are no obvious symptoms of the disease until day 4 when the larvae start to swell and become glossy. The larvae stop feeding around day 7 as they begin to die.

Seven days is the maximum spray interval through peak egg hatch.

4 hours of lab irradiation reduced granulosis virus efficacy against codling moth from 90% to 25%. The 4 hours of irradiation is equal to about 7 days of sunlight.

Weekly applications showed no statistical difference from Guthion.

While overall >97% of the control (untreated) larvae formed deep entries, <35% of virus killed larvae stings were >3mm.

Let me explain that last statement. While granulosis is very effective at killing codling moth larvae it’s not a fast acting contact material. It’s a stomach poison. The fruit incurs damage from the first few bites of the worm (small stings).

So why use it if it allows damage?

For organic producers it’s certified organic.

In any program it will help reduce persistent, problem Codling Moth (CM) populations. Research has shown that an application of granulosis causes CM to be more susceptible to any stress it incurs. Over-wintering stress alone caused populations exposed to granulosis to have a significantly lower emergence (survival) the follow spring when compared to the untreated. It has also been documented to improve the performance of any insecticide.

Zeal – A new miticide from Valent. Labeled for apples, and pears. A molting inhibitor that stops egg, larva, and nymph development on contact. It also acts against adults by sterilizing them. The active ingredient, extoxazole is in a class by itself making cross resistance unlikely. The label allows for only one application per season. It has a 12 hr REI and a 28 day PHI for pome fruits.

Many of the new products are more life stage specific in their mode of action. If you try one in your program this year, make sure that you know the proper timing for the material and how long it will last!

As Always….Please give me a call with any questions!

Larry

234-3424