California – Almonds – Shaking Approaches – AgFax

“Ants can cause substantial damage to almonds at harvest if populations are present in the orchard. With an insect growth regulator (IGR) ant bait, you can make the application 4 to 8 weeks before harvest starts. It takes longer for an IGR to affect populations, but it provides extended control. Some ant baits can be spread up to 2 weeks before harvest if growers cannot use IGR baits. Remember, don’t irrigate orchards 48 hours before and 24 hours after bait application because wet bait isn’t as attractive to ants.

“Mite activity increased in walnuts this year, and the dry heat might have triggered that. Growers spraying for husk fly and codling moth should add a miticide if their monitoring indicates high mite activity. Also, consider predator populations in making decisions and follow UCIPM mite guidelines.

“Husk fly is prevalent in areas with a history of it. Husk fly tends to be a more sporadic insect, and activity has been pretty normal this year. It can stain the shell of the walnut. In a year like this, where we expect high yields, growers who sell inshell need to be more aware of husk fly populations.

“As almond and walnut harvest approach, plan to take field harvest samples. Grade sheets will lay out insect damage and levels of concern. However, grade sheets show only half of what is going on in the field, and those reports don’t provide specifics about the type of damage. Field harvest sampling completes the picture.

“Take field samples of 500 to 1,000 nuts per block, then use what you find with those crack-outs to make important management decisions for the following year.”

Franz Niederholzer, UC Farm Advisor, Colusa, Sutter and Yuba Counties

“The second hull split spray is starting this week and will probably run into next week. Growers are mostly utilizing solid field sprays this go-round as opposed to the first spray where some only sprayed the Nonpareils.

“We are currently at 1,600 degree-days at the Nickels Soil Lab and are picking up 20 to 25 DD/day. If the second generation starts on the new nuts, we should see the third-generation eggs at 1,800 degree-days from biofix. So, this is the critical time to carefully monitor for NOW populations. If the Nonpareil is ready to shake before the third generation arrives, that would be ideal.

“Mites are a consideration for growers as harvest approaches. If mites flare up before harvest, they can cause leaves to drop, which prolongs nut drying on the orchard floor. Partial defoliation at harvest also can reduce flower bud development for next year. At the same time, late-season mite flareups are expensive to control with short pre-harvest interval (PHI) knockdown miticides. Also realize that PHI interval is measured from shake date and not picking up timing.

“Growers are beginning to spray orchard middles to prepare for harvest. Most put on a fungicide with the first hull split for hull rot protection.

“Alternaria symptoms are showing in specific, higher humidity areas. Infections probably started towards the end of June. During that period, high nighttime temperatures in the Sacramento Valley extended the dew hours.

“In walnuts where botryosphaeria is a problem, the window for a one-spray bot program is closing. It runs from late June into early July. If a two-spray program is needed, Dr. Themis Michailides (plant pathologist, Kearney REC) recommends that the second spray go on later in July or in early August, which puts it about a month after the first spray.

“Traps at Nickels show traces of codling moth, but no husk fly have been noted yet.

“July is the recommended timing for the third nitrogen application in walnuts — 25% of the annual N budget.

“Clingstone peach harvest is underway along Highway 99 in south Butte and Sutter Counties, and prunes are a month away from harvest in our area.”

Dan Prentice, Prentice Ag Consulting, Bakersfield

“Growers are working on their second hull split spray. Most started their first spray on or just after July 4. Probably 20% to 25% of my growers won’t do a second spray this year. Those blocks are mostly in areas that traditionally have minimal NOW damage, so the absence of a second spray won’t be detrimental. But some growers also are trying to cut back on costs due to lower almond prices.

“We started sampling almonds this week and have found small traces of worms on edge trees, but most of the nut samples have been very clean. Trap activity after hull split is generally sporadic. Egg traps tend to have no activity and then you find one trap with 70 to 80 eggs right next to traps with none. But once Nonpareil harvest begins, we will see more egg-trap activity.

“All of our growers did include a miticide in the first hull split spray. Isolated blocks have already received two miticide applications since mid-June and still show high pressure. If mite populations continue to build through August, it could be concerning for growers. Mites need to be under control in the next couple of weeks to avoid an ugly situation.

“Most growers did some form of deficit irrigation during hull split, and they will go back to full irrigation once they finish the second spray. A few growers continue irrigation through July and will end up harvesting on the later side as a result. Fields also need dry conditions for spray activity. Growers have been applying herbicides for weed clean up, and orchard floor preparations are underway ahead of harvest.

“Growers will begin shaking a few isolated almond blocks next week, sometime around July 22 or July 23. These are mainly towards the south end of the valley, and those blocks are always on the early side. More growers will begin their first shaking towards the end of July, but activity will start on a more widespread basis into the beginning of August.

“Pistachio orchards started showing mealybug pressure in the last couple of weeks. Mainly, we’re seeing this in blocks that received a mealybug spray earlier in the year and where we knew the populations were present. Over the last week, citrus flat mite started coming in, as well. The populations are low, and we will continue to monitor to see if a treatment is necessary.

“Pistachio kernels continue filling, and a couple of pea splits are already popping out. It is a tad early to see this, but not far off of average timing.”

Aaron Heinrich, Independent Crop Advisor, AgriWest, Inc., Escalon

“Growers are right in the middle of the second hull split spray for Nonpareils. The first treatment started close to July 4, and they’re following up with the second spray 10 to 12 days later to protect further splitting nuts from the second NOW generation.

“At a minimum, all growers will apply one spray, but many will put on two sprays. Some third treatments will be made based on flight activity this year and pressures in the past. Growers with high numbers in egg and pheromone traps may need that third application to aggressively control NOW. With the low value of almonds lately, the price can weigh on growers as they make the best decisions before harvest. Winter sanitation, of course, is always the first and best line of defense for NOW.

“Mite pressure has been very slow starting this year. In certain fields, we can’t find a single mite, while activity is increasing in others. In areas where mites are building, we’ll add a miticide to the second hull split spray. Growers hope to treat now to clear out mite populations through harvest.

“Growers are finishing ant-bait applications as we approach harvest, and they are managing orchard floor preparations and herbicide spraying.

“Small traces of rust are showing in Stanislaus and San Joaquin Counties. Rust starts early on in tender tissues, then warmer temperatures can bring on rust situations later in the season.

“During hull split, growers stretch out irrigation schedules and go back to full irrigation after the last spray.

“We are taking tissue samples in mid-July in almonds for a general analysis on micro and macronutrients, then determine orchards’ post-harvest needs. Hull samples at harvest are also critical for checking boron.

“Walnut growers started treatment for husk fly last week. This week, we see a few more husk fly in traps. We will treat fields with a history of husk fly issues. However, pressure appears less than average compared to previous years for husk fly, codling moth, mites and walnut aphid. We generally have sprayed several blocks for aphids and mites by now, but they are really just starting to show up.

“Growers are at the tail end of the second codling moth flight. We did treat a few fields with high numbers. In areas with high mite populations, we did add a miticide to the second-generation codling moth treatments.”