David Doll0 commentsJanuary 12, 2017General, Horticulture, Weeds

Dormant Practices and Wet Weather

Over the past week, a lot of rain has fallen across California. Orchard access should be limited during periods of wet soil to reduce soil compaction as well as stuck equipment. Limiting access, however, creates challenges in performing a variety of orchard operations, including the list below.   Winter Sanitation. Removal of almond mummies from trees is critical for Navel Orangeworm management (NOW). Many operations usually wait for the first rains to help with leaf drop and to help “loosen” the mummies. In wet years, however, it becomes difficult to winter shake the trees as orchard conditions remain too wet for access of shakers. Furthermore, the “window” to winter shake is limited on the late end as fruit bud loss increases as trees enter delayed dormancy and buds swell (Mid to late January, depending on location). To manage this limited access, operations should consider poling crews. If these aren’t available, and sanitation is not performed, a spring timed (usually late April through early May) insecticide can reduce overwintering NOW. This strategy is not as effective as winter sanitation, but is better than doing nothing. Insecticide sprays targeting NOW in the dormant period are NOT effective due to NOW pupae being inside of the almond mummies. Planting bare root trees. Hand planting crews have an easier time than machine planting due to limited field access. If planting delays occur, trees should be placed into cold storage at the nursery as soon as possible to reduce the risk of leaf out and weakened trees. Keep trees in cold storage until ready to plant. Unless there is no other option, do not take delivery of trees in bins or plant them in a temporary location at the farm. On delivery, check tree roots to make sure they are healthy and living (should be

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David Doll13 CommentsDecember 14, 2016Horticulture

Sun Reflecting Products for Increased Winter Chill? 

Written by Bob Beede (UCCE Kings County, Emeritus) and David Doll (UCCE Merced) Tests of winter applied kaolin clay or calcium carbonate-based materials intended to either reflect solar radiation or diffuse it continue.  Results from David Doll, UCCE Farm Advisor, Merced County, and Valley Orchard Management, showed an increase in chill portion accumulation and a 200 to 250 pound increase in CPC yield over untreated trees when kaolin-clay was applied prior to the 2015 season. More can be found here.  The data thus far suggests that spraying these materials to mitigate the negative effects of warm winter temperatures does not assure you of a normal crop, but it might prevent NO crop! This past winter, Carl Fanucchi and Bob Beede collaborated with ORCAL, the company which manufactures ultra-fine, dry ground calcium carbonate, which is marketed in liquid form as Mask® and Diffusion®. They performed UNREPLICATED screening trials in two locations; one in Buttonwillow, and the second east of Highway 99 on Pond Road.  The screening trials included single and double applications applied January 12 and February 12.  A December treatment was planned, but the field could not be accessed.  Flower bud temperatures were monitored in treated and untreated areas using tiny thermocouples inserted into the buds without causing their death.  The resulting data showed bud temperatures were reduced by as much as 100F, and the rate of heating during the morning hours was also slower.  Calculations indicate that the January treatment increased chill portion accumulation by about 13%, due to the lower bud temperatures.  Weekly rating of the treatments for bud break and bloom were also performed.  The treated trees emerged more evenly, and the second treatment of Diffusion applied in February delayed development by four to five days.  The single January treatment developed at about the same rate as the untreated. 

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David Doll3 CommentsDecember 14, 2016Horticulture

Winter Chill Update: December 2016

Written by Bob Beede, UCCE Kings County, Emeritus. Editors note: This article was developed with high chill crops, particularly pistachio. Almonds aren’t as chill dependent, but the broad topics discussed are relevant to all perennial horticultural crops. Those of you who are outside every day know that it has been pretty warm.  The only cold weather occurred during the first week of December in which many locations within the Central Valley experienced three to five days of temperatures ranging from 30-320F.  The Colusa CIMIS station reported 260F the morning of December 6.  Table 1 provides the chill portions for various sites throughout the Valley between September 1 and December 13 for the past four winters, as well as 2010 in which over 70 chill portions were accumulated by February 15.  This exceeds the 58-60 chill portions estimated to satisfy the rest requirement of the Kerman cultivar. The Peters male may have a chill portion requirement as great as 65.  The values in parentheses are the total chill portions accumulated by station and year.  2013 and 2014 were significantly warmer than 2010, in which dormancy was well satisfied throughout all areas of the state.  The 2015 data shows good chill accumulation was well on its way throughout the Central Valley in mid-December, and continued cold temperatures through January contributed to the record 2016 crop.  In contrast, 2014 was already showing deficient chill accumulation at several locations by mid December.  The Arvin/Edison and Coalinga stations might be considered the “canary in the coal mine” for early assessment of future low chill winters.  As you can plainly see, chill portion accumulation is not good thus far, and in some locations, less than the 2014 winter. Table 1. Chill portion accumulation for various CIMIS stations statewide from 9/1-12/13 for selected years. Numbers in parentheses are

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David Doll2 CommentsNovember 21, 2016Horticulture

Almond Orchard Row Width

A question is commonly asked about optimal orchard row width for almond orchards in order to maximize production and returns.  With the goal being to maximize production as early as possible, many operations want to plant rows as close as possible, but wide enough to provide access for equipment.  Therefore, most operations within California plant between 21-22,’ with some orchards as close as 20′ and wide as 24.’ With row spacing, are maximum production and equipment access the only variables in making this decision? Mostly, but one must balance the possibility of increased production with increased costs of establishing and maintaining more rows at a denser row spacing.  When deciding on spacing, there are many other factors to consider, including the cost of increasing row density, the varieties and rootstock selected for planting, expected orchard vigor, anticipated cultural practices, and risk of inclement weather at harvest. Each one of these are outlined in further detail below. Establishment and operational expense. As the width of the aisle decreases the number of rows per acre increases. With an increasing number of rows, establishment and cultural costs also increase (the more rows the more risers, irrigation line, and passes made per acre).  Changing row width by one foot changes the number of rows by one-half row per acre (assuming a square acre planting). This means that in comparison to a 22′ spacing, a 21′ row spacing will cost an additional $750 per acre for the life of the orchard based on pricing from local companies and the UC Cost Studies ($200 establishment through the third year+ $50/year*22 for a 25 year orchard lifespan). Varieties. The tree architecture and vigor of certain varieties can facilitate closer spacings. Upright varieties such as ‘Independence’, ‘Aldrich’, ‘Fritz’, and ‘Padre’ provide the ability to plant tighter as they provide

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Franz Niederholzer0 commentsAugust 8, 2016Horticulture

Catch frame shaker sets in almonds?

Almonds are typically shaken to the ground by a side mount or boom shaker, allowed to dry where they fall for several days to weeks — depending on drying conditions and ant pressure – and then windrowed and picked up.  Once nuts are on the ground, no water should be applied to the orchard to avoid wetting nuts on the ground.  Depending on local conditions – how dry the soil was ahead of harvest as well as weather after shaking, if irrigation is applied between harvests of different varieties, etc.  – traditional harvest practices can result in water stress in the orchard, leading to measurable yield reduction in future years. Recently, some growers have moved to shaking and sweeping within 24 hours. The windrows are then conditioned (picked up, leaves and dirt blown out and dropped back on the orchard floor in a wide, shallow windrow) and left to dry out in the orchard middles.  Growers with micro- irrigation can irrigate (at least a little) once the windrows are down, reducing water stress in the orchard compared to a traditional shake-dry-windrow-pickup harvest.  This practice can reduce the time between shaking and pickup by 48 hours. Another alternative to traditional almond harvest is the use of catch frame shaker sets instead of shake-to-the-ground (no catch) machines (see photo).   Catch frame shaker sets (two machines; a shaker side and a receiver side) are used to harvest prunes and pistachios up and down the state.  Recently I watched a stock prune/pistachio catch frame set harvest almonds in a mature (10th leaf) orchard on Lovell rootstock on Class 2-3 soil at the Nickels Soil Lab near Arbuckle.   This orchard recently had the buried drip hose replaced and the orchard floor surface was rough under the trees.  A catch frame harvest was used to get

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David Doll0 commentsJuly 28, 2016General, Horticulture

Stockpiling Almonds During Harvest

With the increase in almond plantings over the past few years, processing delays will become more common. While waiting to be processed, almonds are usually stockpiled. Stockpiling has a number of advantages,  including getting the almonds out of the orchard sooner to allow the ability to perform  post-harvest practices, reduce in-field insect infestations, and allowing greater flexibility in scheduling transport to the processor. When stockpiling, make sure that the total moisture content (In-hull almond) is less than 9%  (Hulls should snap when bent). Choose a location which is suitable for drainage in rainy weather and that is not near equipment or fuel storage.   Stockpiles should be oriented in a north-south direction to aid in drying and covered with white-on-black tarps. These practices reduce humidity and day-to-night heat fluctuations, leading to a reduction in condensation. Monitor humidity and open the tarp when appropriate to reduce condensation and mold formation. Also monitor  and treat for  insect, bird, and rodent pests. If rain threatens, ensure piles are covered . Finally, be aware that stockpiles are a potential fire hazard. Stockpiles should be fumigated to reduce insect infestation. NOW is an excellent storage pest and can survive in stockpile conditions. Furthermore, this pest can continue to feed and reproduce within stockpiles, increasing damage as well as aflatoxin risk. Although time consuming, fumigation is critical in killing larvae and eggs, reducing damage. Finally, be wary of too much moisture in stockpiles. Studies have shown that hull moisture above 14% and a holding temperature greater than 120°F will increase the risk for concealed damage, mold, and aflatoxin. With an earlier harvest, stockpiles will be exposed to higher temperatures. If needed, delay harvest until nuts can dry. This will be increasingly necessary as orchard canopy coverage increases as cooler temperatures and more shade increases dry times. Avoid

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David Doll6 CommentsMarch 14, 2016Diseases, Horticulture

Yellow Trees and Saturated Soils

Annually, several calls regarding poor tree growth and “pale trees” are received. This is often due to saturated soils. Too wet of soils reduces the movement of oxygen into the soil, killing fine feeder roots. This impacts the ability for the tree to uptake water and nutrients, leading to micro-nutrient deficiencies, impacting nut set and tree growth. Later-season effects are also observed and include a limited rootzone, leading to severe water stress during hull-split and harvest. The problem is often compounded by farm practices. Too early of fertigations before the tree begins to “suck” water from the soil can lead to an increase in saturated conditions. Spring rains, cool temperatures, and heavy soils compound the problem. Once the symptoms appear, the reaction is to fertigate or chemigate in attempts to manage the symptoms of stunted growth and yellow leaves. Symptoms continue to worsen. Recovery is not always possible. If conditions are prolonged, the symptoms will worsen. Trees may eventually die or shed leaves and crop. In some cases, the roots and crown may become infested with Phytophthora. In many cases, Phytophthora is serving as a secondary problem, infecting only after the tree has been weakened by the saturated soils. The problem can be alleviated by warmer temperatures which increase the transpiration rate of the tree or reduced irrigation until the tree recovers. Recovery is dependent on severity, and may take several months. Optimally, it is best to do what is possible to prevent the symptoms from occurring. Prior to the first irrigation, moisture levels in the soil should be dropping. This can be determined with the use of a shovel or auger, pressure chamber, or soil moisture sensors. If using the pressure chamber, irrigation should be considered if trees are 1-2 bars more negative than baseline. More on using the pressure bomb to

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David Doll17 CommentsMarch 7, 2016Horticulture

Almond Set and Nut Drop

Annually, I receive several questions on nut set. Many are aware that not all of the flowers on the tree will set a nut, but how many do? This, of course, can range  between 15-40%.  Most orchards, however, set between the 20-30% range, with average orchards around 25%. This percentage varies year-to-year, and is dependent on flower density, temperature at bloom and post-bloom, and tree health. Spur dynamics play a key role in fruit bud density and the ability for a flower to set. Research by Tombesi and colleagues found that a fruiting spur, if maintained in a position with ample light for photosynthesis, tends to alternate bear. These spurs may flower the year after cropping, but rarely set a nut. This is believed to be due to carbohydrate and nutrient depletion within the spur. Surprisingly, tagged spurs that double or triple crop die, regardless of light position. Therefore, orchards that have a high set percentage deplete the spur pool, leading to a reduced set in the following year (i.e. alternate bearing). Generally, however, most orchards are able to re-develop spur positions which lead to sustained yields. Farmer practices come into play in developing and maintaining spurs- they include PROPER irrigation and nutrition, as well as adequate potassium levels to reduce spur mortality. Tagging studies have also found that set percentage is generally inversely related to flower density. This means that trees that have fewer fruit buds/flowers will set at a higher percentage than trees with a high fruit bud/flower count. This most likely is due to a greater amount of resources able to be allocated to a fewer number of buds. This compensation for the lower bud count, however, does not typically lead to a higher yield. Temperature can impact set as well. Almond pollination and fertilization can occur over

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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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