Weather conditions are making a huge turnaround, from cool and wet to hot and probably dry. It will be a May to remember. Rainfall totals hit records and temperatures dropped to levels more common in April. Images of funnel clouds whirled around on social media.
Fungicides have been going out on a wide basis. With all the rain in May, many growers and crop advisors are taking a cautionary approach, even if they don’t normally apply a fungicide in this time period.
Pests are quiet. Rain and cool temperatures slowed development and movement. But with hotter temperatures ahead, that could change.
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Nick Groenenberg, Independent PCA, Hanford:
“Miticides have been going out. We’re either finished or in the process of wrapping it up (as of 5/31). We’re including minor elements with the spray. I could find some mites and it also was pretty much time to make that application.
“Trees look really clean as far as disease goes but we did include a fungicide because of all the rain. Just because you don’t find any problems doesn’t mean they can’t develop. This would be the year for it.
“Some fields sustained hail damage on May 19. In places, it looked like the hail knocked off 60% of the nuts, while in other areas it took off 20% of them. That was in a block with 640 acres. The storm that moved over that block caused pretty severe damage across a wide area.
“The storm hit trees hard, wiped out some cotton and decimated the tomatoes. That was on a Sunday and plenty of people were calling their crop insurance agents the next Monday and Tuesday. In those almonds, we’re still trying to farm through.
“In pistachios, we’re just starting our mealybug sprays and will include minor elements. All of the pistachios that could have mealybugs are being treated. We’re not treating some of the younger blocks where mealybugs haven’t turned up yet.
“In cotton, the oldest fields are at about 10 nodes and will receive their first Pix application next Tuesday. With this run of cold weather, cotton stopped growing for a while but it’s beginning to get on track again. When the fields dry up enough, we’ll start setting up for irrigation.
“Where the hail pelted cotton, some of it probably will come back but we also have cotton that won’t. That’s also the case with tomatoes that were hit by the hail.
“In alfalfa, we’re trying to cut between rainstorms. No rain is in the immediate forecast, so people are cutting again. Our last rain was on Sunday, May 26. One ranch got 1.33 inches, so it’s still drying out.”
Mark W.F. Carter, PCA, Agri-Consultants, Los Banos:
“Almonds are almost finished filling. Depending on the area, we received one to two inches of rain last week, and we had rain off and on for 10 days.
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“I’m right in the middle (as of 5/31) of applying a fungicide for rust and scab in my older almonds that are closed in. We did not have hail but some pretty hard rain fell in places. There was no damage to trees but in Chowchilla the rainwater was standing, less so in Los Banos.
“Overall, the trees look really good, with the exception of where we had bacterial blast early in the season. We’re wrapping up our last fertilizer this week and I always try to complete that by the last of May. We’ll wait now for hull split, which should be around the end of June. Temperatures are supposed to move into the high 90s and low 100s next week.”
Franz Niederholzer, UC Farm Advisor, Colusa, Sutter and Yuba Counties:
“We’re right on the edge of a switchover in the weather – from unusually cool conditions in the second half of May to what looks like a very warm first week of June. The forecast says we could see mid-90s to low 100s by the middle of next week.
“Some spray rigs were going yesterday (5/30). If any of that included a fungicide, it may have been in anticipation of predicted rain, although it turns out rain only fell in certain areas yesterday evening, mainly on the east side of the valley.
“It’s hard to say how much disease might come out of these last two weeks of wet weather. Temperatures were unseasonably low. Based on one report, the high for last Saturday (5/25) set a record for the lowest high on that date. And now the forecast has highs up to 102 for next week. Currently, most orchards should have good soil moisture, but this rapid warm up will make it hard for trees to acclimate. I expect to see some sunburn in prunes and perhaps some fruit or nut drop in stressed orchards.
“In walnuts, it’s nearly time to start putting up husk fly traps. It never hurts to be a bit ahead on that. A little mesophyll collapse has developed in walnuts. It’s a response to cool, wet weather, although it can be mistaken for blight.”
Jhalendra Rijal, Area IPM Advisor, Northern San Joaquin Valley:
“We’re finally moving into something like California weather for this time of the year – mid to upper 80s and then up to 100 next week. So, things will likely change pretty significantly in a 10-day period, which also will affect insect activity.
“In terms of NOW, moth trap captures this week were minimal, which isn’t surprising. We hit a peak flight around the end of April and the first week of May, and we’re in the tail end of that flight. With the heat, we probably will see an increase in that number next week, at least a little.
“None of the growers or PCAs I’ve talked with this week reported any issues with mites, although with hotter conditions we might expect some activity next week. However, in the last 3 or so years we haven’t had much in the way of mite issues in the upper San Joaquin Valley, at least not until later. Where mites developed earlier, it tended to be in hot spots within orchards, maybe in trees along dusty roads or where abamectin or a pyrethroid were applied early in the season.
“As you scout for mites, also take into account the presence of sixspotted thrips, a good beneficial insect in terms of mites. Use yellow sticky cards to monitor for them. In the last 2 years, I’ve seen these thrips populations in almost all of the almond orchards we monitored. Even in April and into May it hasn’t been unusual to find big numbers of them on sticky cards.
“This period of cooler temperatures slowed down mite development, so those thrips might be enough to control mites even later into the season.
“Codling moth activity has been slow in walnuts, again due to cooler temperatures. Biofix for codling moths’ first flight in the Modesto area was set 2 weeks later (4/16) than we had it in 2018 (4/1), so the progression of the flight was obviously delayed.
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“This last round of cooler weather has added more of a lag. While the 1B flight has already started, these recent cooler conditions have pushed back the 1B treatment timing (600 to 700 degree days) for the flight. At one point, it was set on May 24 but now the timing is more like May 28 to June 2.
“Please keep in mind, that with low codling moth pressure, overall, the majority of orchards may not need spraying at all. Follow your trap counts and degree days to make that decision. Also, remember to sample nuts for codling moth damage, especially at the end of each flight. That is equally important for damage assessments. Follow the UCIPM guidelines for that.”
Tony Touma, PCA, Bio Ag Consulting, Bakersfield:
“A grower by the Grapevine said he’s measured over 4 inches of rain in May. I did some research and it looks like the last wet May on record for Kern County was in 1998 and that total was 1.3 inches. Around Shafter and Wasco, it’s rained 2 inches at a minimum this month and in spots it’s probably been more like 3 inches.
“Last Saturday a big hail storm heavily damaged table grapes near the Grapevine and enough rain fell that people couldn’t walk in the field the next day. Damage to almonds there was minimal, as it looks now. We found some nuts on the ground but nothing significant.
“The weather is warming up and today (5/31) it’s supposed to reach 90. Most of us are very mindful of diseases, so fungicides are going out on a wide basis. We’re trying to get ahead of rust and keep it from blowing up in our faces.
“Alternaria is getting worse in places where we typically have it. You can see it moving and it looks like it will be a problem by harvest. At least right now, we don’t have terrible disease issues, but rust and alternaria will likely advance with this heat and humidity.
“Mites are in the background and their presence really declined with all the rain. Basically, we’re looking toward hull split. With the cooler weather we’ve been through, I expect it to be a good 10 days later than usual.
“This is a beautiful almond crop and hopefully we can get it to harvest without any huge problems.
“In pistachios, we’ve also been monitoring for disease. I haven’t seen anything significant and a lot of growers applied a fungicide within the last 3 weeks just to be on the safe side. So far, so good. Ordinarily, we wouldn’t apply a fungicide on every acre, just where we’ve had issues in the past.
“In cotton, lygus counts have been running 8 to 9 in places and we started treating yesterday. This isn’t widespread but I’m sure the activity will pick up over the next 2 to 3 weeks. A lot of grain is being harvested and lygus probably are coming out of that. Cotton, like almonds, is probably running 2 weeks behind.
“With all this rain, I’m really surprised that we’re not seeing diseases across most of our crops. That doesn’t mean it can’t happen in the next 2 to 3 weeks, but I would have expected more rust by now. I work a lot of wheat for dairies and would have expected rust to get bad in that crop. It can cut yields in half in worst-case situations.
“But I’m finding zero rust in the wheat, not even one plant. Some of those varieties have tolerance to rust, but in a heavy rust year, they can be overwhelmed by it.
“Some rain-sensitive crops have clearly been hurt. I suspect that much of Kern County’s cherry crop has been damaged by the rain, and the same goes for blueberries.”