Fall Foliar Fertilizers: Targeted v/s General Approach

A PCA asking me the other day what I thought of a general micronutrient (iron + molybdenum + zinc + copper + manganese + boron +?) compared to a standard zinc + boron spray program that is common in postharvest almonds in the areas where I work. This question got me thinking about a review of fall fertilizer programs in general, with a focus on foliar nutrients. There are more than a dozen mineral nutrients essential for plant growth. However, only a handful of those nutrients have been shown to be important – in general — to profitable almond production. These

September 19, 2012

Pyrethroid v/s Reduced Risk product usage for Hullsplit/May Spray

A few people have inquired about the differences between spray product choices for worm control during Hull Split and/or “May” Spray. I thought I would highlight some of the thoughts that the UC has developed over the years regarding this decision. Some of this may be redundant, but hopefully some new points will be brought to the table. Which product is best?Determining which product is the best treatment option for your orchard depends on budget, pest pressure, timing, and familiarity. Pyrethroid products are effective in knocking down adult moths and killing larvae that come in contact with the product. Persistence of the product within the field is not as long as the reduced risk products (about 2-5 days less), but they are useful for later hullsplit applications – around 2-5% for optimal timing. The downside with pyrethroids is the assumed mite flare up, knock down of orchard beneficial insects, and water run-off issues. A miticide should be tank mixed with the hull-split application if applying a pyrethroid. “Reduced risk” products (i.e. Entrust, Success, Delegate, Intrepid, Belt, etc.) target the eggs and larvae of the moths. They do not knock down adult populations as well as pyrethroids, but control developing larvae more effectively and selectively. These products tend to persist within the orchard a little longer, providing longer control and thus can be applied earlier than pyrethroid products (when blanks split). They have a minimal effect on beneficials, allowing the natural predators to help control mite populations, usually preventing a mite flare up, thus not requiring the tank mixing of a miticide.  These products are very effective but resistance to the mode of action may occur – so chemical class rotation is important if products are sprayed more than once per season. Water impacts appear to be minimal. Currently, a pyrethroid treatment is cheaper

July 26, 2010

Speed doesn’t kill: Slow down your spray rigs!

As we prepare for hull-split, I thought I would take a minute to discuss spray rig speeds. It is easy to hurry with the hustle of applying a hull-split spray on a large number of acres, but attention should be payed to the ground speed in which chemicals are applied. The University of California recommends applying your sprays at a ground speed of 2.0 MPH to ensure adequate height coverage and canopy penetration of the spray. This recommendation has been based on numerous studies using ground rigs at varying speeds applying a water spray to water sensitive paper placed within the trees canopy. Figure 1 shows data from a recent trial conducted by Joel Siegel (USDA-ARS) conducted in pistachio. Figure 1: Spray coverage of a ground rig applying a water spray to water sensitive cards at 3 different ground speeds. Spray coverage for almond trees is based on the height and density of the tree. For the most part, if the height of the tree is under 10 feet, adequate spray coverage can be attained at almost any reasonable speed. For taller orchards, however, this is not true. As shown in figure 1, the difference of a 1/2 mph (2.0 mph v/s 2.5 mph) can reduce the coverage by 30% for trees 18′ or higher. Traveling at 3.25 MPH, less than 2% coverage was achieved at a height of 20 feet. This reduction makes the pesticide applied lose its efficacy due to low concentration and basically renders the application useless. It also increases the chance of resistance formation, loss of crop due to disease/insect damage, and tractor/rig damage. Many people say that their rigs are better than the ones used in the study and therefore they can go faster. I would doubt that statement unless they can clearly demonstrate it

June 22, 2010