Q&A: Evaluating a Water Supply for Suitability to Irrigate Nut Crops

After receiving the results of a water analysis, there are several components that need to be reviewed to determine suitability of the water for the planted crop. If the water does not meet the expected suitability range, it may require ammendments (e.g. gypsum or acid) or mixing with other water sources to prevent crop loss. Below are five questions that are usually asked when reviewing a water sample as well as some other information regarding a water analysis and conversions. Does the salt concentration (ECw) pose a potential problem (osmotic effects)?  Crop  Unit Degree of growth or yield reduction None Increasing Severe Almond and Walnut dS/m <1.1 1.1 -3.2 >3.2 Pistachio dS/m <4.0 4.0 – 8.0 >8.0 Are there specific elements (B, Cl, and Na) that could accumulate to potentially toxic levels?  Element  Unit  Crop Degree of growth or yield reduction None Increasing Severe B (boron) mg/l (ppm) Almond and Walnut <0.5 0.5 – 3.0 >3.0 Pistachio <4.0 4.0 – 10 >10.0 Cl (chloride) meq/l Almond and Walnut <4.0 4.0 – 10 >10.0 Pistachio <20.0 20 – 40 >40.0 Na (sodium) SAR(none) Almond and Walnut <3.0 3.0 – 9.0 >9.0 Pistachio <5.0 5.0 – 10 >10.0 Na (sodium) meq/l Almond and Walnut <4.0 4.0 – 7.0 >7.0 Pistachio <20.0 20 – 40 >40.0 Could the water chemistry contribute to unstable surface soil structure and lower water infiltration rates?  Lab Information  Unit Potential of Water Infiltration Problems Developing Unlikely Increasing Likelihood Likely Ratio of SAR/ECw ratio <5.0 5.0 – 10.0 >10 Ratio Ca/Mg ratio >2.0 2.0 – 1.0 <1.0 Could the water chemistry be prone to plugging drip emitters, microsprinklers, or filters?  Lab Information  Unit Potential for Water Infiltration Problems Developing Unlikely Increasing Likelihood Likely ECw dS/m <0.8 0.8 to 3.0 >3.0 HCO3+CO3 meq/l <2.0 2.0 – 4.0 >4.0 Mn (manganese) mg/l <0.1 0.1

May 16, 2015

Leaffooted Bug Advisory for Almonds

Written by Kris Tollerup and David Haviland University of California Cooperative Extension and UC Statewide IPM Program Pest control advisors need to be on the lookout for leaffooted bug. All indications are that 2015 has the potential to be a significant year for leaffooted bug damage to almonds.  This prediction is based on observations of very high populations of LFB during the fall of 2014 and a high overwintering survival rate due to mild winter weather.  During the past few days (~March 15th) multiple reports from across Kern County have been sent to UC Cooperative Extension offices that PCAs are starting to see movement into crops.  Although no known reports of leaffooted bugs have occurred in the mid and more northern growing areas, it would be prudent to begin monitoring now. Monitor for LFB at least once a week from mid-March through May, and then every one to two weeks through June.  The most effective monitoring method is to do a visual survey for the presence of bugs.  This can be done by using a long pole to knock branches in the upper tree canopy, causing the bugs to fly such that they can be seen or heard. Visual inspections should be coupled with inspections of the fruit by looking for gummosis on the almond hull.  However, by the time gummosis is seen, damage has already occurred.  Gummosis can also occur due to physiological damage.  Therefore, if the method is used, cross-section the area with gummosis to determine the presences of a pin-sized discolored wound caused by the penetration of the insect’s mouthparts.  Also inspect fruit on the ground for the presence of gummosis and a stinging wound to determine if LFB is the culprit.  Be sure not to confuse gummosis caused by LFB (clear to light amber color) with

March 20, 2015

Chilling Requirements in Chill Portions for California Crops

Part 3 in the series – What can we learn from the low chill winter of 2013-2014 In my last post, Counting Chill Better – Using the Chill Portions Model, I discussed how the chill portions model (also known as the Dynamic Model) is different from the chill hours model. Now that you can figure out how much chill you got in chill portions, how much do you need? Below is a table of the estimated chilling requirements of most of California’s major tree crops, and a few particular important cultivars. Most of the requirements listed below are based on scientific research. A few (*) are estimates based on how much chill we got last winter and how the crops responded in the spring and at harvest. If you are interested in the requirements of cultivars not listed here (especially for apricots, cherries, peaches and nectarines) or want to know the scientific reference information for a particular estimate, check out the more thorough version of this list at the UC Davis Fruit & Nut Center site.

January 22, 2015

Is Last Year’s Warm Winter the New Normal?

Katherine Pope, UCCE Farm Advisor Sacramento, Solano and Yolo Counties Part 1 of 3 in the series – What can we learn from the low chill winter of 2013-2014 With harvest wrapped up, it’s a good time to take stock of the impacts of the warm winter of 2013-2014. Average chill was down 25% in the Central Valley, falling behind in January and never catching up. Orchards in many crops showed classic symptoms of low chill – delayed and extended bloom, poor pollinizer overlap and weak leaf-out. Prolonged bloom likely resulted in some cherries, pistachios and prunes experiencing warmer bloom temperatures, which decreased yields for many. Drought-related water stress likely contributed to some of the yield, size and quality issues we saw at harvest. But low chill was almost certainly responsible for a great deal of the unusual tree behavior, low yields and poor quality. So what can we learn from this tough year moving forward?

November 8, 2014

Pros and Cons of Earlier, Warmer Spring

A few discussions this week around an “earlier” than normal year for insects and nut development. We are somewhere around 10-12 weeks post bloom in the Northern San Joaquin Valley. Nut developing is progressing as expected. We have experienced higher than normal temperatures during stage one of growth which may lead to sizing issues – especially in later blooming varieties (i.e. ‘Fritz’) – similar to what we saw in 2013. Endosperm development should begin or has begun in most ‘Nonpareil’ and pollinator orchards. I suspect that kernel fill will be earlier, leading to an earlier ripening/hull-split/harvest timing.

April 17, 2014

Dormant Weed Control in Tree Nut Crops 2014

by Mick Canevari, Brent Holtz, and Brad Hanson Current dry weather has preempted most normal winter weed germination and growth while prolonged periods of dry soil has caused some early weeds to desiccate and die.  In most tree and vine herbicide trials conducted so far this winter–the untreated controls look similar to herbicide treatments, very clean and without weeds.  What to do at this point poses some interesting questions.  Will it rain? Most of us are worrying more about irrigating our almond trees this summer than controlling weeds right now. If you have some weed growth that germinated with rain our one December rain, or with fall and winter irrigations, you may want to apply a post-emergent herbicide now in order to prevent hard to kill weeds from becoming established.  The warm weather could allow these weeds to establish and become more difficult to control, impacting the success of later herbicide applications by increasing trash on the berm and reducing coverage. 

January 27, 2014

Leaffooted Plant Bug

I have been several calls in regards to leaffooted plant bug (Leptoglossus clypealis and L. occidentalis). Damage has been reported from various areas of the county, with significant damage observed within some blocks. Leaffoted plant bugs get their name from the leaflike features found on the back legs of the large nymphs and adults. Adults are about 1 inch long and have  a yellow or white zigzag line across their back. Females lay eggs in strands which are often found on the sides of almonds or pistachios.

May 10, 2013

Dormant Weed Control in Tree Nut Crops 2012-2013

 Written by Mick Canevari and Brent Holtz, UCCE San Joaquin. Weeds have a tremendous capacity to spread within an orchard.  The first line of defense is  identifying the weeds you need to control, and selecting the best herbicides or cultural practices to control those weeds.  If you use the same herbicide(s) each year, a shift to tolerant weed species will ultimately take over and a loss of herbicide effectiveness will occur.  Alternating products with different modes of action at least every couple years will improve results and insure herbicides long term viability.  The UCIPM web site has charts that show which weeds are controlled by what herbicides, and an excellent weed photo gallery that includes many weed species commonly found in California for easy identification and reference http://www.ipm.ucdavis.edu/.      

January 9, 2013

Winter Chill Reduction from Climate Change

I came across these papers discussing the reduction of winter chill due to climate change within the central valley of California: 1. Luedeling E, Zhang M, Girvetz EH (2009) Climatic Changes Lead to Declining Winter Chill for Fruit and Nut Trees in California during 1950–2099. PLoS ONE 4(7): e6166.  2. Baldocchi and Wong (2008). Accumulated winter chill is decreasing in the fruit growing regions of California.  Climatic Change. March 2008, Volume 87, Issue 1 Supplement, pp 153-166.

January 4, 2013

What did I learn at the Almond Board’s annual conference?

The Almond Board of California’s annual conference is a chance to connect with others in the almond industry, listen to world class researchers talk about their work, and check out a huge almond-focused trade show all at one event. The 2012 meeting was last week (Dec 11-13).  Here is a quick review of some of the things I picked up from researchers and informed industry members at that meeting…

December 21, 2012