If you farm pistachios, it’s likely you have a sprinkle of almonds in your portfolio, and if not, you probably have an almond neighbor and know that the two commodities influence each other in terms of Navel Orangeworm (NOW), and an understanding of what is happening firstly in almond is important as we go into pistachio spraying and approach harvest. Let’s first establish some constants in terms of knowledge about sanitation:

• Sanitation is the most important practice in controlling NOW 

• Sanitation may be hindered by inclement weather and/or inability to remove or destroy nuts

• Almonds can be harder to remove from trees but easier to destroy once on the ground

• Pistachios can be easier to remove from the tree but harder to destroy once on the ground

The lack of almond sanitation in 2023 due to lack of access due to rain, inability to afford sanitation, or fields abandoned caused catastrophic losses in terms of NOW inedibles. Some processors average inedible percentages were as high as 6% with reports of growers with 20, 30, 50% damage.

Sanitation of 2024 was far more successful in terms of nut removal and destruction than 2023. Trapping thus far in 2024 is also generally lower in total catches and flights are generally shorter in duration than in 2023 (Fig.1). With optimistic prices of almonds around a blended $2.00/lb in 2024, growers have spent money on mummy protection of almonds at flight 1, quieting flight 2 at almond Nonpareil hull split. Flight 3 catches have been generally very light on my traps, and pollinator or delayed Nonpareil sprays were generally made and conversations I am gathering from other PCAs echo similar strategies. Early reports of NOW damage in almond are less than 2023, but not completely absent. One processor reported 2.9% on their first 2 million pounds of Nonpareil. My crackout reports will be presented in the next publication, as I personally have only begun to windrow nonpareil, but will generate some data from the field prior to USDA reports. The two types of data don’t often match, but a field crack out is a good assessment of where we stand, and can lend to some assumptions of pressure heading into pistachios.

Fig. 1. 2023 (top) vs. 2024 (bottom) trapping and degree day accumulation.  Note catch range of 2023 much higher than 2024, and flight 1 in 2023 was nearly two flights and much longer duration than 2024.

All of this sets the scene for flight 4 and overlapping generation pressure, which is usually what causes pistachio NOW infestation, although we see early/pea splits right around the start of flight 3 (mid to late July) but the economic threshold of applications at this timing in pistachios is not well studied and less-often treated with insecticide unless there is another factor driving a spray. Golden Hills hull degradation and slip begins slightly earlier than Kerman (usually the first week of August) and increased exponentially throughout this month, whereas Kerman hull degradation is usually quite linear over a longer period. As the hull degrades and slips from the shell and kernel, it becomes attractive and vulnerable to NOW infestation. The onset of slip usually occurs between flights 3 and 4, but there may be some light activity, depending on a number of variables I can dive into another time, but crop protection for NOW usually begins after some level of slip has occurred. With an exponential hull degradation in Golden Hills, single-shake harvests are far more common than Kerman, and usually less crop protection is needed as well. Your PCA will likely recommend a larvicidal material such as Intrepid 2F, Altacor Evo, or Spear Lep, combined with a broad-spectrum pyrethroid for adult knockdown.

The rule of thumb I generally operate around with multiple applications, is to only count on two weeks of residual control of any of the larvicidal materials and plan another one to maintain protection up to harvest. If you have determined a harvest date of 9/1 on Golden Hills, then an application at 8/15 will usually be fine, whereas with Kerman of a harvest date of 9/15, two applications on 8/15 and 9/1 could be an adequate solution. Sometimes it may also be advisable to spray between shakes depending on what is left on the tree.

One thing to keep in mind is the value of quality bonus as paid out by individual processors. Many processors begin to deduct $0.05/lb at .25% of insect damage and scales up from there (Fig. 2). The perspective to consider is that even at a historically acceptable insect damage percentage of .25%, at 4000lb/ac yield, the bonus loss is $200/ac. Figure 3 gives an idea of how much money comes off the table with consideration of bonus schedule losses. The consideration of actual crop percentage loss ramifications is less financially significant as quality bonus, and figure 4 shows that the approximate economic threshold of crop loss exceeding the cost of treatment (~$70/ac) at 4000lb/ac yield is at 1.00%.

Fig. 2. Quality payment schedule example, pistachios.

Fig. 3. Quality bonus losses in terms of dollars per acre with various levels of yield.

Fig. 4. Actual crop loss from insect damage at $1.80/lb.

As always, discuss these items with your PCA and come up with a comprehensive plan of protection with a harvest date in mind. I am here to facilitate conversations as needed to discuss this surface level information in more depth.