David Doll4 CommentsFebruary 24, 2012Horticulture

Some Thoughts on 2012 Bloom

To date, the weather has been very warm, with conditions favoring bee flight and pollination, but not the various bloom time diseases. The bloom looks strong across the county. In other words – so far, so good. I have received a few calls from a variety of topics, and will post some thoughts on these topics. Next week, there looks to be a few showers moving into the area, so fungicide coverage may be needed to prevent various diseases – especially if a fungicide application hasn’t been made. If an application has been made, it should provide protection for 10-14 days, dependent upon the amount of rain received. Delayed Varietal Bloom, Weak Bloom.I have received several calls regarding delayed bloom of Monterrey and Fritz. Although these thoughts are conjecture, discussions with a few advisors concluded that post-harvest tree conditions/ practices may be the cause for these issues. Tree conditions include defoliation of trees last fall from scab and rust, water stressed from a delayed harvest, and inadequate rainfall during the dormant period. Practices that may have encouraged this separation include delayed application of nitrogen and water during the post-harvest period, and missed pre-irrigations this past winter due to lack of water. Also consider that these trees have had high yields over the past few years – with two years of delayed harvests (mid-Sep-Oct) with Fritz/Monterrey. Many people have asked about inadequate chilling being a possible cause, but ample chilling has been received. More importantly, if it was a weather effect, we would expect to see the variations in bloom time occurring across a wide area – not just in a single orchard. For example, one orchard has had an issue with the delayed bloom, while the neighboring orchard with the same varieties is blooming as expected. Birds Eating Blossoms?Catching me a bit

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Brent Holtz9 CommentsJanuary 17, 2012Horticulture

Plant New Trees High!

Written by Brent Holtz, UCCE San Joaquin CountyOne of the worst things that can happen to young trees from nurseries is that they are planted to deep. Sometimes  they are initially planted at the right height, but then a berm is thrown up around the trees and their crown (the graft union between the scion and rootstock) is covered with the soil from the berm. I saw many diseased trees last spring that had Phytophthora root and crown infections and every one of them had their graft union below the soil line; sometimes the union was more than six inches below. If you are planting or replanting, trees should be planted high on small mounds as shallowly as possible. Planting depth after settling should be no deeper than in the nursery, and the graft union should always be well above the soil line. Try to follow some of these planting tips: 1. Dig a hole deep enough so the roots are spread out and not cramped, 2. Plant the trees so that the nursery soil line is above the current soil line, 3. Plant the highest root a little above the soil line and then cover it with extra dirt, and 4. When planting allow for 3-6 inches of settling in the planting hole. I have never seen trees die from being planted too high, but I have seen many trees killed by being planted too low. This is especially true in heavy soils with a high clay content. These soils have slow water percolation, drain slowly, and remain saturated longer than well drained sandy soils. The mound around the tree trunk forces excess water to drain away from the tree, thus reducing the length of time the crown is exposed to excess surface moisture. Saturated soil conditions can occur

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Joe Connell2 CommentsNovember 20, 2011Horticulture

Observations of Krymsk-86 Rootstock

Written By Joe Connell, UCCE Farm Advisor, Butte County Krymsk 86 is a peach-plum hybrid rootstock (Prunus persica x P. cerasifera) that originated in the Krasnodar region of Russia. As such, this hybrid rootstock is different than any other rootstock in use in the California almond industry. Now that it is planted in commercial orchards under many different conditions we are learning more about how it behaves when grafted to almond. When grafted to peach, plum, or apricot it is thought to be tolerant of cold temperatures, drought, water logging, resistant to phytophthora, and somewhat resistant to lesion nematodes. It was observed to be precocious, productive, and appeared to increase fruit size. Now that it is grafted to almond in California we are discovering that trees behave differently than almond grafted on peach rootstocks and differently than almond grafted on Marianna 2624 plum. In fact, it behaves uniquely like almond grafted on Krymsk 86. The first trial in Butte County including this rootstock was planted in 2003. Just completing their ninth growing season, the Nonpareil trees on Krymsk 86 are larger than adjacent trees on Lovell peach. What we know so far is that Krymsk 86 appears to be compatible with almond and it has a vigorous root system with good anchorage as a young tree. Krymsk 86 roots are susceptible to root knot nematodes and this will limit its usefulness in the San Joaquin Valley and on light textured soils where root knot can be a problem. In sandy soils in Stanislaus County, trees on Krymsk 86 are less vigorous than trees on peach roots. In spring 2011, soils were wet and cold for an extended period causing trees to get a slow start. Several young orchards had yellow trees showing up on Krymsk 86. Trees were yellow for

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David Doll2 CommentsMay 20, 2011Horticulture

Monterey Drop

Throughout California growers have seen significant drop within their Monterey variety. Discussions this past week within our in-service farm advisor tour concluded that this drop is most likely due to cold damage.Cold temperatures, in the low 30’s, were experienced (and confirmed) in April throughout the Sacramento and San Joaquin Valleys. Although we are not certain, the damage observed appears to be an abiotic (non-disease) issue due to the following evidence:1. Drop has been observed in multiple regions of California,2. Drop was observed in multiple orchards with varying cultural practices,3. Damage in some orchards appears to be in the lower spots,4. Nuts are without disease symptoms of any kind,5. The problem appears physiological. Through the process of elimination, Joe Connell (Butte Co Farm Advisor) began to consider cold damage. Upon looking back at the records, he noted that cold temperatures were experienced for several nights. Since varieties differ in their cold sensitivity, not all varieties were affected. Information regarding the sensitivity of Monterey to cold has not been researched, which leaves the possibility of this variety being more sensitive to other commonly planted varieties (i.e. Nonpareil, Butte, etc.). Connell’s thoughts were supported by observations from Roger Duncan (Stanislaus Co. Farm Advisor). If you are concerned about the drop you are experiencing within your almond orchard, please call your local farm advisor to discuss the various reasons in order to reduce the possibility of re-occurrence.

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David Doll2 CommentsMarch 1, 2011Horticulture

Frost Damage in Almonds

Several calls were received today in regards to the symptoms of frost damage. Temperatures in several areas of California were cold enough to cause damage. Many growers have implemented frost protection strategies, but surveying the orchard still needs to occur in order to determine the amount of damage. Damaged blossoms/almonds will be apparent by dead or darkened tissue. Symptoms will become apparent within 72 hours of the frost event, usually appearing 24-48 hours after the event. When viewing the flowers, looked for water soaked areas that might not have yet turned brown. Symptoms will range, but any damage done to the female parts of the flower will most likely lead to flower abortion/loss. Check all parts of the tree, both at eye level and in the upper canopy in order to determine the extent of crop damage. Since frost damage is an abiotic disorder triggered by the environment, keep in mind the following patterns to help discriminate it from other bloom time issues (i.e.Brown Rot):1). Damage is present over a large area of the orchard,2). Damage is present across varieties – especially if both were in the same bloom stage. This may not be true if one variety is yet to bloom and was in the pink tip stage during the event,3). Damage is associated with known topographical changes, i.e. a low spot,4) Tissue of the blossom is darkened, with no obvious signs of fungal growth. The tree’s sensitivity to frost changes with the various bloom stages. The tree is most tolerant to frost when it is dormant or in pink tip. As the tree begins to bloom, it becomes more sensitive to frosts, with the fertilized flowers or small nutlets being the most susceptible. With fertilized embryos, the jacket may protect the ovary/embryo from damage. Here are some pictures of frost damage:

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David Doll0 commentsFebruary 24, 2011Horticulture

More info in Regards to Frost Protection

I received the following question and thought the response was important enough for an entry:“… The forecast shows that 28 and but also chance of rain for the same night. Does that mean we will moisture from the ground to hold the temperature up. Would that mean no irrigation is needed?” Response:Most likely, it will be a clear night in order to drop to 28F. If not, the event would be considered an advection frost event, which are very difficult to provide protection as the wind displaces the heat gained by the various strategies. It is correct to assume that if the surface of the soil is wet from rain, that irrigating more to wet the soil surface will not provide too much of a benefit – i.e. flood and/or drip systems. This is especially true if the surface water freezes. Once the water freezes, heat will no longer be released. Keep in mind that drip system lines may actually freeze if volumes are not high enough (less than 15 gallons/minute/acre). If volumes over this rate can be applied, drip systems may provide some benefit. In regards to micro-sprinkler or solid set systems, applying water during the night will provide a heating effect even with a wet soil surface. This effect is due to the heat that is released off the water as it freezes. In essence, with these systems, more water equals more protection. Targeted amounts of water should be 30-40 gallons per minute per acre. Minimally, water should be applied at rates higher than 15 gallons/minute/acre to avoid freezing of the spaghetti tubing/ irrigation lines. These rates were determined through research conducted by Joe Connell (UCCE Butte County) and Richard Snyder (UCCE Specialist).

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David Doll0 commentsFebruary 18, 2011Horticulture

Cold Temperatures Expected this Weekend

Cold weather is expected for Saturday night. As of now, temperatures are expected to drop below 32F. If the weather is as predicted, temperatures will not drop much below 30F. At this temperature, almond buds, blossoms, and young fruit should be safe. I wrote an entry last year covering this topic as well as frost damage prevention. In brief: Almond Susceptibility to Frost. Generally speaking, the further the tree advances out of dormancy, the more sensitive to frost it becomes. A dormant tree is very tolerant to cold temperatures, while small nutlets are very sensitive to frost damage. At this point of the growing season – petal fall to early nutlet development – temperatures below 26F will cause significant to total loss of the almond crop, while temperatures above 28F will cause minimal damage to the crop. The small difference of 2F makes the difference, and is why frost prevention strategies can be used to reduce crop loss.Frost damage prevention. Growers can manage their soil moisture and ground cover to help reduce frost damage from a radiation frost event.Click here to view the entire article.

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David Doll0 commentsFebruary 5, 2011Horticulture

Supplemental Pollination – What we (don’t really) know

I had a few questions this week about supplemental pollination to increase the amount of compatible pollen available for almonds. Mainly, the growers were asking about the feasibility of increasing compatible pollen in orchards with only one pollinator variety or in orchards with greater than 50% Nonpareil. Here was what I was able to dig up: Research: – Work conducted by Robbin Thorp determined that application of supplemental pollen by modified ground rig, helicopters and beehive inserts did not increase fruit set or yields in orchards with adequate cross pollinating varieties; – However, a 2006 study by Tom Gradziel indicates there may be benefit when using hexane washed pollen (removes sticky pollenkit and the pollen does not clump) dispensed at the hive entrance. In this experiment, trees were caged and pollen parentage was tracked. They found that 6% of the almonds were pollinated with the washed pollen. Comments: In many of the older trials, pollen sourced for the experiment had questionable viability. It is important to know if the pollen is viable and able to germinate, form a strong pollen tube, and fertilize the almond embryo. Pollen viability is not the only limiting factor; stigma receptivity also affects nut set. This is why flowers are the most receptive to pollen within the first few days after opening and explains why an extended bloom usually means a reduce crop. It may be reasonable to try to provide extra pollen, delivered by honey bees, when there is no other variety providing overlapping bloom. It is important to note that it is extremely difficult to determine if the extra pollen improves crop production. Studies (paternity tests) have demonstrated that supplemental pollen is able to fertilize the embryo in orchards where they have been applied. Then again, how can you prove that those nuts

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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 CommentsJanuary 11, 2011Horticulture, Insects

Bee Health and Pollen Sourcing: Does mixed source pollen improve bee health?

A study conducted by Ramesh Sagili at Oregon State University looked at pollen sourcing and the effects on bee health. In this study, equal amounts of single-source pollen and multi-sourced pollen were packed into the comb cells of six frame hives. Each week, 100 newly emerged paint bees were introduced to the hive, while 20 nurse bees were removed from the colony for a protein estimation of the hypopharyngeal gland. This gland produces special food that is necessary for the development , metamorphosis, and pupation of the larvae. They also measured the brood area occupied by the eggs, larvae, pupae, pollen, and honey. Figure 1: Mean hypopharyngeal protein content of 20 nurse bees. What did they find?Analysis of the hypopharyngeal gland protein content yielded interesting results. Not only did they find a statistically lower gland protein content within the single-source pollen packed hives(Figure 1), but they also detected statistically lower amounts of crucial enzymes within the proteins isolated from single-source pollen packed hives (Figure 2). Differences brood size was also apparent; colony growth measurements were significantly lower within the single-source pollen packed hives (Figure 3). So what does this mean? Figure 2: Concentrations of two enzymes found within the hypopharyngeal protein of 20 nurse bees  Findings from this study suggest that pollen from a diversity of sources will benefit hive health. Beekeepers should keep this in mind when determining the feeding regime for the hives. It doesn’t stop there, however, as growers should attempt to incorporate alternative pollen sources within their orchard system to help increase hive health. Strategies may include placement of hives next to hedgerows or vegetative strips, or leaving an area of clover, or some other cover crop, un-mowed during and after the pollination period. It would be best to leave the un-mowed area outside of the orchard

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