David Doll8 CommentsFebruary 15, 2016Horticulture

2016 Almond Bloom Considerations

Adequate chill and recent warm temperatures have accelerated almond bloom. Timing is close to “normal” in southern and southwestern areas of the State, but are 1-3 weeks ahead further north. Below are some thoughts to keep in mind with the anticipation of rain this week. Authors note (2-16-2015): There has been some concern about the wording around the time of nutrient/boron sprays and bloom. Research has shown that boron applied postharvest to 10% bloom can increase yield, while applied later than 10% bloom will not have an impact. Nutrient sprays-with the exception of boron as described in the previous sentence- have not been found by researchers to increase yield when applied at bloom. Sorry for the confusion. Fungicides are usually effective for about 14 days after an application. This period of protection is decreased with rain events. Furthermore, as surface areas expands – whether it is the flowers or leaves – newly exposed tissues are unprotected from infection. This means that spraying too early may not provide the wanted protection. If planning to make a fungicide application, apply the material as close to the rain event as possible. Remember that it needs between 30-60 minutes to dry. Depending on the pre- and post-rain conditions, and the periods of leaf wetness, a fungicide spray may not be needed. Keep in mind that fungal diseases require several hour periods of leaf wetness – which comes from fog, dew, and rain. Be cautious with adding additional surfactants. Most fungicides have surfactants mixed with the active ingredient. Adding additional surfactants may impact the efficacy of the fungicide, damage the flower’s tender tissues, or impact bees. The label should indicate if a surfactant is needed. Avoid tank mixing in boric acid with sprays made during bloom when bees are active(1). Researchers at the University of California as well as around

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Franz Niederholzer2 CommentsJanuary 25, 2016Horticulture

Wet or Dry, Get Ready for Bloom

Franz Niederholzer, UCCE Farm Advisor, Colusa/Sutter/Yuba Counties Spring isn’t here yet, but it will be before we know it. What happens then, weather-wise, and how you react to those conditions could change the season for your operation. But, no one can be certain of the weather this spring. Will it be wet? The forecasters think there is a good chance for that. If that’s the case, more bees and bloom sprays, and less irrigation will be needed. But, they could be wrong and 2016 could be another dry year. Better plan for a wet or a dry spring. Here are some things to consider: Topic Wet Dry Bees Higher hive stocking rates (3 hives per acre, minimum of 6-8 frames, with one frame of brood) are recommended in wet years. Spray carefully. No difference from the last few years. Make sure bees have water sources and fungicides are applied with bee health in mind. Click HERE1 for link to Almond Board BMPs for bees. Bloom sprays With rain at bloom, UC recommends 2 bloom sprays – pink (5% bloom) and full bloom. If it is warm at bloom, use material(s) with anthracnose activity. If it continues to rain, more fungicides will be needed. The more fungicides used, the greater the need to rotate chemistries. Click HERE2 to see info on fungicide efficacy/timing/resistance management. One bloom spray, timed before or at full bloom will provide good disease control under dry (no rain) bloom conditions. Weed management Properly selected and applied preemergent herbicides, sprayed before rain saturates orchard soils, provides weed control when you can’t get into too-wet orchards. Pre or post emergent sprays will control weeds. Don’t fall behind. Controlling weeds saves water. Nitrogen management 20% of annual N budget should go on by mid-March. If it’s still raining after petal

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David Doll6 CommentsFebruary 17, 2015Horticulture, Irrigation

More Leaves than Flowers: Why?

I have received a few reports about poor bloom conditions on ‘Nonpareil.’ In these cases, flower density appears to be low and leaves are starting to push (See Figure 1) indicating that the fruit buds did not develop over the past year. From the reports, trees tend to be between the ages of 6 and 12 years old and have been observed across Merced County. A number of issues may be responsible, including the following: Water stress. Reductions in water resources over the past year have led to reduce vegetative growth in many orchards. This lack of growth prevents the formation of vegetative buds (in-season) which develop into fruit bud (post-harvest through dormant period). Research has shown that spurs that remain in good light positions tend to “take a year off” after bearing fruit, while others receiving too much shade die. Therefore, canopy growth must be maintained to some extent to keep crop loads high. Salinity Induced Water Stress. Increasing soil salinity decreases the osmotic potential of the soil, making the plant “work harder” for water. This leads to water stress and reduces the energy diverted into vegetative growth and floral bud development. High yields over the past few years. Trees producing large yields in successive years have been observed to have an “off year.” This is due to most of the plants energy being diverted into the crop load, reducing the amount available for developing new fruiting spur positions. As discussed earlier, if this happens in successive years, the number of viable fruit spurs may be reduced leading to a reduced crop. Re-leafing in the Fall after leaf drop from foliar disease, salt, or mites. Bloom density would be lower if the tree defoliated last summer or fall from lack of water, too high of salt levels, foliar disease,

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David Doll4 CommentsFebruary 7, 2015Diseases

Almond Bloom 2015

Bloom is around the corner. After receiving adequate chill units through December (almonds need ~400-500), almonds switch from ‘chill accumulation’ mode to ‘heat accumulation mode.’ Although less is known about this stage for many crops, it is known that a certain amount of heat is needed in order for bloom to begin. This heat requirement keeps the plant from blooming too early, reducing the risk for the impacts of frost events. The warmer weather over the past few weeks, however, has provided conditions that have met the heat requirement for most areas of CA. This suggests that if the weather stays warm through the next week, bloom will begin for more areas within California. Below are some considerations to have in mind for bloom: Fungicide sprays. Due to the sensitivity of almond flowers to disease and conditions during bloom that are conducive for disease, most people will spray a fungicide during this period. In wet conditions, multiple sprays may be needed, while in dry years a single or no spray may suffice. Conditions that favor disease formation include wet weather, warmer temperatures for Brown Rot, Anthracnose, Bacterial Spot, and Shot-hole, cool weather for Botrytis, and heavy dew. Fungicide selection should provide coverage for the diseases of concern (Please see this link and scroll to ‘Almonds’). Bloom sprays should be applied before rain events to provide protection for flowers, flower parts, and emerging leaf tissue. Coverage from a fungicide spray will last around two weeks, unless significant rainfall occurs.  If applying prior to a rain event, applications will need a few hours to dry to prevent “run-off.” In rainy weather, follow-up sprays will be needed every 7-10 days. Some varieties – such as ‘Butte’ and ‘Carmel’- are more susceptible to disease and may require a spray even in dry weather, while others – such as

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David Doll9 CommentsJanuary 30, 2015General, Insects

Honey Bee Considerations at Bloom

There has been a lot of concern about honeybee health related to fungicide and insecticide applications within orchards. More is being learned every year about the impacts of pest management practices on hive health. Recently, The Almond Board of California released an excellent resource titled “Honey Bee Best Management Practices for California Almonds.” This resource provides an overview of the research conducted and the recommendations generated from the results and conclusions. The following is a brief overview of these practices that are associated with insect and disease control around bloom: Read the pesticide label carefully – including surfactants – and avoid any chemicals that indicate toxicity to bees. Avoid applying or tank mixing any insecticides during bloom until the effects on bees are known. Treatments for peach twig borer should be considered prior to bee move-in or after hive removal (i.e. delayed dormant, “May” spray); Avoid the fungicides iprodione, captan, or ziram. These fungicides negatively impact bee hive health; Apply fungicides later in the afternoon or evening when bees and pollen are less present. It is also important to also not spray too late that the fungicide does not have a chance to dry before the next foraging day; Addition of adjuvants is not needed unless specified by the fungicide label. These compounds may harm bees by increasing fungicide activity; Cover or remove the bees’ water source and avoid spraying the hive directly with any pesticides. More information can be found at The Almond Board of California. Keep in mind that these spray practices are independent of good bee hive care, which includes provision of water in during dry bloom periods, sources of pollen.nectar in bee holding areas, and of course, good communication with your beekeeper.

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Franz Niederholzer3 CommentsFebruary 7, 2014Diseases, Horticulture, Insects

Pollen, Bees, R.U.L.E.S., and Almond Bloom

Almond bloom has begun.  No time of the season is more important to delivering a good crop.  You don’t get a Mulligan at almond bloom.  Good pollinization, delivery of viable pollen grains to the flower stigma of a compatible flower, is the first step of a successful bloom season.  Keeping spray materials off the pollen helps keep the pollen viable for germination (the next step in a good crop) and healthy for bees—the key pollinators from Red Bluff to Bakersfield.

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David Doll0 commentsFebruary 15, 2011Diseases

Some more bloom time thoughts…

Yesterday, I had a nice chat with Dr. Jim Adaskaveg, UC Specialist in Plant Pathology. As many of you may know, Dr. Adaskaveg conducts many of our foliar and bloom disease trials. Here were some additional comments to be added about bloom spray timing and last week’s post. Dr. Adaskaveg highlighted that all parts of the flower are susceptible, but for the most part the flower petal is the most susceptible and is the primary point of flower infection. Many of the fungicides used have what Dr. Adaskaveg termed “Reach Back Potential.” This basically means that a fungicide application controls the growth of infections that may have occurred BEFORE the fungicide application. In these cases, the fungicide does not serve as a curative, but rather as a fungal-static agent, or, in other words,  it slows the growth of the fungus but does not kill it. This provides more time for fertilization and petal abscission to occur, thus reducing brown rot incidence. He also pointed out that Brown Rot is most active in temperatures above 57 degrees F. It is important to note that infection can still occur below 57F, but the rate of growth is reduced. He suggested that growers with brown rot tolerant varieties (i.e. Nonpareil) and no history of brown rot may be able to get by with a minimal spray program. In some cases he observed 50% Nonpareil orchards in which the grower did not spray the Nonpareil; fungicides were applied only to the pollinators. This practice was not recommended for Butte plantings. Butte is very susceptible to brown rot. In regards to the upcoming weather and the beginning of bloom, he suggested holding the first spray until after the rains, trying to hit the 30% bloom mark on Nonpareil.This should provide coverage for the emerged Sonora blossoms. He felt comfortable with

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David Doll2 CommentsJanuary 27, 2011Horticulture, Nutrient

Bloom Spray Additives: Do they work?

Bloom is approaching. Several questions about whether or not bloom spray additives increase flower pollination and set have been asked. I will try and answer them the best I can using information from previous trials across the state. Much of this information is gleaned from Roger Duncan’s presentation delivered at the 2010 Stanislaus Almond Day. Should I include foliar nutrients in the bloom spray?Several trials from four different advisors from areas across the state (Duncan – Stanislaus, Holtz-Madera, and Edstrom – Colusa, and Viveros – Kern) have indicated that nutrients and other additives included with bloom sprays do not increase yield of almonds in properly maintained orchards. In most trials, yields of the untreated control were higher than the foliar nutrient applied treatment. These were multiple replicated trials held over several years. Materials used can be seen by viewing the presentation linked below. This trial data can be seen in Roger Duncan’s 2010 NSJV Almond Day presentation (click link). What about Pristine® Fungicide?Pristine® fungicides is a boscalid/strobilurin mixture that has been used successfully for several foliar fungi that commonly affect almond flowers and leaves (i.e. Brown Rot, Rust, Scab, etc.). There is evidence that suggests that Pristine® causes a yield bump when applied during the bloom or post bloom period. Research by Jim Adascaveg (UC Riverside) and Roger Duncan (UCCE Stanislaus) tested this hypothesis and have not found a significant increase in yield from a bloom or post bloom Pristine® application. It is important to state that in Duncan’s trials (Stanislaus Co.), the yields were higher in treatments containing Pristine®, although not statistically significant. Duncan found this same insignificant yield bump when applying Gem®, another strobilurin, in the post-petal fall period. Conversations with a local consultant indicated mixed success of the Pristine® yield bump across his multi-year trial. Although he

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David Doll2 CommentsMarch 2, 2010Insects

Fungicides and Bee Health

I have had a lot of questions/concerns regarding bee health and bloom fungicides sprays. Even though bloom is nearing its end, I thought I would try and answer a few questions I have received – and finally had some time to research and formulate an answer to these questions. Do fungicides applied during bloom affect bee health?The short answer is “We don’t know.” Research has shown that fungicides that are applied around or at bloom do adhere to the pollen, and are brought back to the hive during the process of pollination. The fungicides then inhibit the growth of different fungi within the bee hive, decreasing the the microbial diversity of the bee’s food source. As of the Almond Board of California 2009 Research Proceedings, it is unknown whether or not the fungi affected benefit or harm the overall health of the hive. Which Fungicides are transported back to the hive?Researchers at the Carl Hayden Bee Research Center in Tuscon AZ found five commonly used fungicides in the bee bread (food source) of hives placed in almond orchards. These fungicides include Chlorothalonil, Cyprodinil, Fenbuconazole, Iprodione, Boscalid, and Pyraclostrobin. The amounts of fungicide appear to vary by orchard and timing of application – BUT – this data was only based on hives placed in three orchards with two or three samplings- for now. Also, it is not known which fungicides target which fungi, if they negatively affect bee health directly, and if they have a negative impact on the entire hive by reducing the quality of the food source. The research group headed by Dr. DeGrandi-Hoffman will be looking into these questions through this year. What about Pristine (Pyraclostrobin-Boscalid) applications?Essentially, we don’t know exactly how this fungicide affects fungal growth in the hive. In vitro studies from Dr. DeGrandi-Hoffman’s lab indicates

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