Navel Orangeworm Management Considerations for 2010 Almond Crop

I have embedded my presentation from the 2010 Central San Joaquin Valley Almond Day meeting this past week. This presentation highlights many of the considerations that need to be made by growers in determining when to spray for navel orangeworm (NOW), what to treat with, and how frequently a spray should be made. I will discuss slides of interest which will hopefully provide some type of commentary as you view the presentation. This is a first, so bear with me...

2010 NOW Management Considerations  
Slide 1: Title Slide.

Slide 2:  General introduction of pest lifecycle. For reference, if needed, please see IPM website. Important points to mention is that almond acreage has expanded closer to NOW original territory, and has provided a host density much greater (10,000 x greater) than the original host of NOW.

Slide 3: Control of NOW is based upon timing of application, coverage of spray, and persistence of the product within the orchard.

Slide 4: All of these factors influence NOW pressure and end of year damage. Varying degrees of sanitation among the pistachio, pomegranate, and fig growers - as well as almond growers - can carry over high populations of NOW into the next growing season. Early harvest can significantly reduce NOW damage as the nuts will be harvested and removed from the orchard before the third flight of the moth begins. Peach twig Borer damage can predispose a nut to NOW infestation - so effective PTB management is also part of effective NOW management.

Slide 5: Talking a little bit more about sanitation. Long term study showing the effect of sanitation on NOW damage at harvest. Note that winter shaking trees to less than 2 mummies per tree significantly reduces NOW pressure without a spray. This study was on the nonpareil variety. Hardshell varieties may not have similar results - BUT NOW from a hardshell orchard can move into neighboring orchards with Nonpareil.

Slide 6: Percentage of survival of nuts from different varieties infested with NOW. The almonds were infested in the field and brought into the lab - probably why the percentage is higher than expected. Note the differing rates and the high survival % within butte and padre. It appears that survival within Padre is within the hull of the almond, while the larvae survives in the nut of the Butte. Another reason why sanitizing/winter shaking those Butte/Padres is important for growers with other blocks/neighbors with NOW sensitive varieties.

Slide 7: Moths can overwinter and emerge from mummies at any time in the season. While most do emerge in the spring, there are significant amount of moths emerging in June and July as well. NOW is always emerging and present within the orchard!

Slide 8: Irregardless of the trap counts in the early season, it appears that NOW syncs up well with the timing of almond hullsplit. Joel Siegel, USDA-ARS researcher, has stated that it is almost like the almond was meant for the NOW - the two, albeit evolved thousands of miles away, have lifecycles that match up well.

Slide 9: Data showing that the newer "reduced risk" pesticides control as well as pyrethroids and organophosphates providing more options for growers.

Slide 10: Timing of differing products: Reduce risk products can be applied a few days earlier than pyrethroids. For the most part, reduce risk products should be applied on the early side of hullsplit - just around the time blanks start to open. Pyrethroids should be applied later at around 2-5% hullsplit. The difference is due to the persistence of each product within the feeding zone of NOW larvae and the ability to control NOW. The later timing for pyrethroids is due to their ability to knock down adult moth populations.

Slide 11 and 12: Research to show the persistence of various products for NOW control. These studies were from laboratory research and it is thought that product breakdown will be quicker within the environment due to UV light, temperature, and other factors. Take home message - Reduce risk pesticides appear to persist a day or two longer in the orchard.

Slide 13 and 14: Coverage differences with Spray rig speed -  covered this topic in last weeks blog. Spray at speeds no faster than 2 MPH.

Slide 15: Slide discussing why bracket sprays are effective. Essentially as the nut splits, more and more surface area becomes available for NOW egg laying. Furthermore, it becomes increasingly difficult to cover all of the areas of the nuts when applying a pesticide. This is why for areas with high NOW pressure, a spray at early hull split and late hull-split will provide greater control than a single spray.

Slide 16: A slide re-iterating the opening comments about knowing the pressure within the orchard. Keep in mind that a well timed, single spray with a proven product applied at 2 MPH will only provide 50% reduction of NOW damage at harvest. If a 50% reduction does not get you below the 2% threshold, than re-evaluation of the listed orchard factors and a 2nd or 3rd spray may be needed.

Slide 17: Conclusions for the 2010 season. PTB 2nd flight appears - at this moment - to overlap with hullsplit. Usually when this happens, NOW damage % increases. If using a reduce risk product, spray on the early side of hullsplit. Generally, for growers in Merced County - with the exception of high pressure areas- one application (and in some cases no applications)  should provide the needed NOW control. Keep in mind that pest management practices need to evolve as we find out more about this pest. It is prudent to consider applications of reduce risk sprays at May to help with NOW population. It may be, although we do not have the research yet to support this, that a single May spray with a non-pyrethroid reduce risk material may control NOW populations for the season. If a pyrethroid product is used within the orchard, a  miticide should be added to control the corresponding mite flare up. For further info, please check the UC IPM webpage on NOW.

2010 NOW Management Considerations

Mid-June Almond Market Outlook

Almond Market Update provided by Paul Ewing at Hilltop Ranch

Almond Update

Posted on June 10th, 2010

Today the Almond Board of California reported:

May 2010 shipments were 91.9 million lbs. 
-  Down 23% from May 2009 shipments of 119 million 
- Domestic shipments were up 19% and exports were down 39%

The market has remained fairly inactive for another month.  Following a few weeks of further declines, pricing was relatively flat for the past two weeks.

SHIPMENTS/DEMAND:

Today’s report brings shipments for the season to 1.26 billion vs. 1.15 billion at this time last season, up 9.7%.  Overall both exports and domestic shipments are up roughly 10%, though exports started out the season real strong and domestic shipments are heavy late in the season.  This huge May vs. May decline in shipments can be attributed to buyers working through inventory and positions world-wide (China off 5 million lbs, Europe off 9 million lbs., Central/Eastern Europe off 8 million lbs., Middle East off 13 million lbs.)

THE 2009 CROP:

Crop receipts as of May 31 were 1.405 billion lbs, still showing the impressive accuracy of the NASS objective estimate of 1.350

THE 2010 CROP:

NASS’s 2010 objective crop estimate is due for release July 8 instead of June 30.   The Almond Board advised recently “USDA’s National Agricultural Statistics Service (NASS) has found it necessary to delay the almond field data collection due to the extremely late maturity of the crop.  Most field crews have not been able to begin their orchard work as they wait for the kernels to mature.  However, the situation is improving with temperatures rising to near normal levels in recent days.“

We’ve experienced a good growing season with plenty of moisture and without extreme temperatures.  The trees appear to have a strong capacity for 2011.   There’s been an absence of stress, which in other years can degrade kernel size or quality (shriveled, etc.)  The hulls and kernels appear to be good sized but we await the NASS Objective report for detailed info on sizing.  We do not know with much certainty this early, but current expectations are for a late harvest.

20/20 RETROSPECTIVE & HAZY OUTLOOK:

During this season, buying patterns have dominated the market trend.  Low but rising prices was the perfect catalyst to cause many buyers to stock up on almonds from October through mid winter.  Then buyers in many markets took a step back to work through inventory and long positions before buying more, which slowed sales at the handler level.  Working through the long positions and big stocks took longer than many expected, in many markets, not just China.  Lately the sense is that in some markets the inventory has been worked through but the downward price trend has caused buyers to delay purchasing decisions.  The economic uncertainties world-wide, especially in southern Europe, has also caused more hand to mouth buying.  

Discussions of defaults in Europe, one UK trader in particular, is hurting market sentiment for the short-term.  Re-sales of abandoned containers have slowed sales at origin.  Though putting it in perspective, if it’s 100 containers, the industry is only dealing with about 3-4 days of EU consumption. 

Spanish almonds have taken away some California almond demand this season, particularly in southern Europe.  The Spanish crop, damaged by frost, is estimated to be much smaller for the coming season. 

May shipments were expected to be weak but this number was lower than we anticipated.  Inventory adjustments up or down can cause such swings for one month, and if the industry can focus more on the big picture, it can take some of the over-corrections out of the market.  Looking at this bigger picture we see a 2010 crop year supply very similar to the 2009 crop and world-wide consumption that appears robust.  We estimate that at some point within 30-90 days a lot of pent up demand will come back to the market and cause a reversal of the current market sentiment.  In the meantime the very near-term outlook remains hazy.

The next position report is due July 9, the day following the NASS objective estimate release.

Questions regarding the report should be directed to Paul Ewing (paul@hilltopranch.com).

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 with water sensitive cards on your farm. Spray trials testing applicator speed have been conducted for over 40 years by several generations of UC/USDA-ARS researchers with a variety of rigs and technologies. All of them come to the same conclusion: Apply your sprays at a ground speed of 2.0 MPH.

I guess, in this case, that speed doesn't kill.

Irrigation Scheduling Part 3 - Taking in account irrigation efficiency

When water is applied to an orchard, loss of some amount of water should be expected. Growers must consider this loss of water when calculating the actual amount of water being applied. This amount will vary on the irrigation system used, soil and climatic conditions, and water management conditions.

Water applied to a field can be lost by run-off, percolation below the root zone, sprinkler spray evaporation and off-target drift. Efforts to minimize these inefficiencies should be employed, and could include longer irrigation sets at lower rates, the construction of tailwater return systems, and/or sub-surface installed systems.

Irrigation efficiency (Ea) is defined as the percentage of applied water that is held in the root zone. Mathematically, it would look as follows:
Ea = water stored/water applied.

Irrigation methods commonly used within the almond orchard include surface irrigation systems such as flood and furrow and pressurized systems that include sprinkler, drip, and micro-sprinkler. As we can see in table 1, irrigation efficiency differs with each system. With surface systems, fast movement of the water from the head end to the tail of the field end usually results in higher irrigation efficiency. Within pressurized systems, distribution depends on design parameters including spacing, nozzle type and size, riser height and operating presure.  Keep in mind that maintenance and filtration affect pressurized systems more than surface based systems. Pressurized systems, however, are usually more efficient due to the reduction of run-off and water loss through deep percolation.

Table 1: Application efficiency typical of various irrigation systems.

System	Ea (%)
Basin/Flood	65 - 80
Furrow	65 - 75
Solid Set Sprinkler	75-85
Microsprinkler	85-90
Drip	90-95

When calculation orchard water use, irrigation efficiency must be accounted or under-irrigation will occur. Below are some examples that show the different water application needs due to difference in irrigation efficiency.

General Information:
Location: San Joaquin Valley
Soil: Loamy Sand
Rooting Depth: 5 feet
Available Water-Holding Capacity (AWC): 0.6 in/ft
Depletion of AWC before irrigation: 50%
Irrigate when AWC reaches 1.5 inches

Flood Irrigation	Microsprinkler	Drip Irrigation
Ea = .70	Ea = .85	Ea = .90
Weekly ET = 1.5 inches	Weekly ET = 1.5 inches	Weekly Et = 1.5 inches
Water applied: 2.14 inches	Water applied: 1.76 inches	Water applied: 1.67 inches
Difference from drip: + 0.47 inches	Difference from drip: + 0.09 inches

Over the course of the crop year, there may be 15 or more inches of water needed to fully irrigate a flood irrigated orchard in comparison to a drip irrigated orchard. If unaccounted, this lack of water will lead to water stress and probably crop loss.

Source: Goldhamer, David. UC Almond Production Manual: Chapter 25 Irrigation Scheduling.  UC ANR Publication 3364.

Irrigation Scheduling Part 2 - Determining Water Holding Capacity

Last week we discussed how to calculate almond tree water usage by using evapo-transpiration data provided by CIMIS. Now that tree water use can be determined, we have to determine the amount of water that can be applied to the soil to maximize irrigation efficiency.

It is important to understand a few terms when dealing and discussing soil water holding capacity.  Soil saturation is when all of the soil pores are filled with water - this occurs immediately after an irrigation and continues until gravity pulls the water through the pores of the soil (Figure 1). Once the soil has drained, usually 1-3 days after an irrigation/rain event, the soil is at field capacity. This water is held against gravity within small pores by the soil particles, and is the largest amount of water that the soil can hold between irrigations. In contrast, the permanent wilting point is when all the available water is gone. The amount of water between the field capacity and wilting point is termed allowable depletion - or the amount water available to the plant provided by irrigations. It is important to note that at field capacity not all of the pore space is filled with water (about 25% air space), and at permanent wilting point not all of the water is removed from the soil (it is stuck to the soil particles).

Figure 1: Differing terms regarding water holding capacity of soils.

Basically, when efficiently irrigating, water needs to be applied to refill the soil profile to field capacity but prevent the loss of water to deep percolation. The amount of water to refill the soil profile is related to the texture of the soil; coarser soils hold less water while fine, heavy soils hold more. This is due to the differing size of soil particles and pore space in these soils. In general, soils are about 50% solids, 50% pore space. The pore spaces hold varying proportions of water and air. Table 1 shows the approximate available water of various soils.

Table 1: Available water for various soil types.

Type of Soil	Range (in/ft)	Average (in/ft)
Coarse(S / LS)	0.6-1.00	0.75
Sandy (LS / SL / L)	1.00-1.50	1.25
Medium (L / SCL)	1.25-2.2	1.50
Fine (SiL / SiCL / CL / SIC)	1.7-2.4	2.00

As we can see in table 1, differing soils have differing abilities in holding water. Therefore, determining how much water can be applied during an irrigation depends on the soil within the orchard. Soil sampling at various depths can help determine the soil texture throughout the root zone. It is advisable to to have soil maps from the NRCS on hand to help identify known texture changes. Root zone depth is usually determined by soil being excavated by an auger/probe, texturing the soil, and checking for roots. Most orchards, if the ground was prepared properly pre-plant will have between three to four feet of root zone. The presence of a clay lense, hardpan, or gravel layer may reduce the root profile depth and water availability to the tree. Once a soil texture profile has been developed, the amount of water that the soil can hold can be easily calculated by using the above table. For example:

Soil Surface	Soil Texture	Depth in Feet	Available Water Holding Capacity (From table1)	Available water in each soil layer (in)
1"-12"	Sand	1	0.6	0.6
13"-24"	Loamy Sand	1	0.8	0.8
25-42"	Sandy Loam	1.5	1.0	1.5
			Total:	2.9

In the example above, we have 2.9 inches available for the tree to use. When scheduling to irrigate, we shouldn't wait till all 2.9 inches are used, but rather base the timing of the irrigation when roughly 50% of the available water is used. Letting the profile go completely dry will deplete all deep soil moisture, affecting tree performance later in the season. Using the assumption of 50% also provides a bit of a "fudge factor," helping to prevent a mistake from being made. So, using the example above, irrigation should be scheduled  when 1.4-1.5 inches of water have been used by tree evapo-transpiration. Please review last weeks entry to help calculate evapo-transpiration.

Knowing the amount to water that can be held within your soil is also helpful in determining how much water is needed to refill the entire rooting profile. In the soil profile used in the example above, irrigating more than 3.0 inches may lead to deep percolation. Deep percolation may be of benefit if  leaching of salts from the rooting profile is desired.

For more information and estimating soil moisture by the "feel" method, please check Kern County's Irrigation Handout. Please email if any question comes to mind.