Posts Tagged: chloride
One, one hundred, one thousand
This little mnemonic, or memory aid, in the title is helpful in remembering the critical levels of toxic constituents in irrigation water. The “one” stands for 1 part per million (ppm) of boron (B), the e” hundred” flags 100 ppm of sodium (Na) and (Cl) and the “thousand” represents the level of total soluble solids (TDS or slats) in water. Levels exceeding the critical values for any of these constituents can present problems for tree growers. The problems typically show themselves as tip-burn and defoliation. The B, Na and Cl are toxic elements at relatively low concentrations, but symptoms appear similar to the damage caused by high salinity.
Water that exceeds the critical levels mentioned in the mnemonic has a greater tendency to cause damage if sufficient leaching is not applied. It doesn't mean the water is impossible to use, only that greater attention needs to be made to ensure that these salts are adequately leached. High levels of these salts accumulate in the soil with each irrigation, and the salts are absorbed by the tree and end up in the leaves where they do their damage.
This promises to be another low rainfall year and the customary leaching we rely upon in winter rainfall is not going to be as effective as in customary years. Irrigation is a necessary evil. Every time we apply irrigation water we apply salts, and unless some technique is used to minimize salt accumulation, damage will result. This damage can be more than just leaf drop, but also the stress that induces conditions for root rot.
Irrigation water has been applied the last four years and many trees looked stressed. Even well irrigated orchards have leaf burn due to the gradual accumulation of salts from irrigation. It is probably necessary to irrigate in many winters. With the lack of rain problem, it may be necessary to irrigate even if there is rain. The wetted pattern that is created by a drip or microsprinkler emitter also creates a ring of salt in the outer band of the wetted patter. If there is less than an inch of rainfall to push this salt down, this salt tends to diffuse towards the tree where it can accumulate back in the root system. Orchards with even good water quality would find it advisable to run the irrigation system with the first rains. Growers with water quality exceeding one, hundred, or thousand should be especially alert to the need to manage water in low rainfall years.
irrigATING CITRUS
Sodium chloride damage on raspberry
A few pictures here for the library on sodium chloride damage on raspberry. Leave tissue concentration of sodium is over 250 ppm and chloride over 20,000 ppm (that's 2% of total dry tissue!). Interestingly accumulation of the micronutrients zinc and copper in these plants is also notably higher than what would be normal for raspberry.
Sodium chloride damage in raspberry. Note heavily burned leaf margins, to the extent that very little green remains.
Entire cane affected by sodium chloride. Appearance of some green leaves on some laterals tells us that this plant can yet recover.
Problems Growing Avocadoes in a Container
Help for the Home Gardener from the CCMG Help Desk
Client's Questions and Problems:
with some webbing as well as some “corky” bark. He also said they have “red ants” on the tree which bite when handled. The container is large, and consists of a mixture of native (clay) soil and amendments. He has poor drainage in his yard hence the need for container. Has plans to plant another variety (Zutano) so will have the A and B pollinators. Varieties are compatible and appropriate for his area. Client uses well water and is close to Discovery Bay and knows about their boron problem, but his well seems fine although he has not taken a recent water test.
CCMG Help Desk Initial Response:
Thank you for calling Master Gardeners with your Avocado problems. The e-mailed photos came through well. Based upon the information so far, we think the most likely cause of the brown areas on the leaves is sunburn and/or windburn. You may have noticed that the affected leaves are mostly on the top and outside of the plant, and there are many unaffected leaves. We have had a few really hot days in recent weeks (these questions and responses are in mid-September). You can provide some temporary shade using a light shade cloth or some other shade structure on hot afternoons - although hopefully we will not have too many more of those to come this year. Also, avocados are quite sensitive to wind, so if they are in a windy area some protection from wind might help. You mentioned that the tree is getting adequate water, and from the photos I did not see problems related to well water - although it may be helpful to get that tested if you see other plants in your garden developing problems. I did see some webbing on the leaves, but it does not seem to be widespread in the tree. I could not tell from the photo if there were insects present, but it could be spider mites, and if this insect presence is only in a small area of the tree, you can wipe them off or use a quick water spray. I am including some UC links which will give some more information on pests and on avocados in general. http://ipm.ucdavis.edu/PMG/GARDEN/FRUIT/avocados.html and http://ipm.ucdavis.edu/PMG/PESTNOTES/pn7405.html
You also mentioned that you had a colony of 'red ants'. Without seeing these I cannot tell you what they are; red fire ants have been found in southern California, and I have not heard reports of them being in the Bay Area, but that does not mean you don't have them. What you are seeing could be red Spider Mites. Here is a link that might help-http://ipm.ucdavis.edu/PMG/PESTNOTES/pn7487.html
If you would like a positive identification on these ants, you could bring a sample into the Agricultural Commissioner's office, of which there is a branch in Knightsen. This link gives their hours and contact information.
http://www.co.contra-costa.ca.us/1542/Agriculture-Weights-Measures
Finally, here are some further links to general avocado culture. The second one has some good information on growing in containers. http://ucanr.org/sites/gardenweb/files/29079.pdf
and http://uccemg.com/Edible_Plants/?ds=530&uid=127
I hope this is helpful, and that you will eventually grow some good avocados.
******************************************************************
CCMG Help Desk Follow-up Response:
After we spoke earlier today, I did some research and learned that avocados are very sensitive to high salt (chloride) and boron levels in irrigation water. Symptoms of chloride toxicity include chlorosis (yellowing) of leaves and necrosis (death) of the tips and margins (edges) of leaves. Symptoms are usually more severe on the older leaves. Boron toxicity causes dark, necrotic areas along the edges of leaves.
Here is a University of California photo that shows how boron toxicity appears on an avocado (left). The right photo shows chloride toxicity effects on an avocado.
The damage on the leaves in these photos look similar to those in the photos you sent previously, so it does seem possible that high levels of salt or boron in the irrigation water could be causing the leaf problems you are seeing on the tree. It is probably worthwhile for you to have the water tested for the well you are using to irrigate the tree. There is the possibility that the drought, or increased (or decreased) pumping of other nearby wells, or changed irrigation practices have affected the quality of your well water.
A list of commercial laboratories that perform water testing can be found at this link on the CCMG web page (http://ccmg.ucanr.edu/files/77177.pdf). You will want to have the water tested for irrigation suitability. It is sometimes hard to navigate the websites for the testing labs and to find a description of the services offered and the charges for the testing they can perform. You might find it easier to call the labs to get the information you need. Be sure to call several before you decide which one to use since the fees charged seem to vary quite a bit. I found a couple that charge only about $75 for the irrigation water test, but some charge twice that much.
Below is an excerpt from tables from the University of California publication entitled "Abiotic Disorders of Landscape Plants" (the original reference document's Table of Contents is at http://www.fao.org/docrep/003/T0234E/T0234E00.htm#TOC) that you might find helpful in understanding the results of your well water test. The data from the tables show maximum levels of salts (chloride) and boron in irrigation water that are generally considered safe. Because the avocado is quite sensitive to boron and salts, any amounts in your well water that are higher than the levels shown below n the table as “generally safe” could cause problems for the tree. If you have the water tested and would like some assistance in interpreting the results, you are welcome to contact us for help.
****************************************************************
Relative Boron Tolerance of Avocadoes: Sensitive @ 0.5 - 0.75 mg/l
****************************************************************
Maximum Permissible Chloride Without Avocado Leaf Injury from Different Rootstock
Root Stock Root Zone (Cle) (me/l) Irrigation Water (Clw) (me/l)
West Indian 7.5 5.0
Guatemalan 6.0 4.0
Mexican 5.0 3.3
****************************************************************
On a different topic, I looked again at the photos showing the rough, “corky” areas on the bark of the tree. It does look somewhat unusual, but I couldn't identify any likely causes. When I tried to enlarge the photo to look closer at the corky areas, the photo became blurry. If you want us to investigate further, perhaps you could send us a “close-up” photo. Also, one possibility that occurred to me is that it might be sun scald. You might want to check to determine whether the side of the tree that receives the most direct sunlight shows more of the rough corky areas as compared to more shaded areas. If the answer is “yes”, it could point to sun scald.
Hope you find this additional information to be helpful. Feel free to call us again if you have additional questions.
******************************************************************
Contra Costa Master Gardeners' Help Desk
Editor's Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523.
We can also be reached via telephone: (925) 646-6586, email: ccmg@ucanr.edu, and we are on the web at http://ccmg.ucanr.edu/
Water Quality and Southern California Agriculture
Assessing water quality for Southern California agriculture typically revolves around the total salinity of the water, its total dissolved solids (TDS), and the toxic ions boron, sodium and chloride. Salts are necessary to plants, because it is in the form of diluted salts that all nutrients are taken up by plants- the macro and micronutrients plants extract from the soil. High salinity leads to water imbalance problems much as if the plant were not getting adequate water. A toxicity problem is different from a salinity problem, in that toxicity is a result of damage within the plant rather than a water shortage. Toxicity results when the plant takes up the toxic ions and accumulates the ions in the leaf. The leaf damage that occurs from both toxicity and salinity are similar in that it causes tissue death known commonly as "tip burn." The damage that occurs depends on the concentration of the ions in the soil water around the roots, the crop sensitivity and crop water use, and the length of time the crop experiences the ions. In many cases, yield reduction occurs. Because crops can not excrete salts the way humans do, salts gradually accumulate in a plant. As a result plants need a higher water quality than humans do.
Much study in many countries has gone into evaluating water for crop use. Some of these studies have been on the effects of salts on soil characteristics. Generally, as sodium concentration increases, a soil will lose its aggregation, eventually leading to poor water infiltration. Many more salinity and toxicity studies have been done on plants themselves. Not all crops are equally tolerant of salinity and toxicities, and in general most plants respond to salinity and toxicities in a similar fashion. If a plant is intolerant of salinity, it will be intolerant of chloride, sodium and boron. Most annual crops are less sensitive to salts than tree crops and woody perennials, although symptoms can appear on any crop if concentrations are high enough. The reason for greater sensitivity for perennial crops is that the tree is sitting in the ground absorbing salts for a longer period than the lettuce plant that is harvested 3 months after planting. Furthermore, deciduous trees like walnut shed their leaves each winter, so they can handle salinity better than evergreens like citrus and avocado.
To manage salinity and toxicities, water management is the key. Depending on water quality, an excess of water will be applied to the soil to leach the previously applied salts away from the root zone. The poorer the water quality, the more excess water is applied.
Selecting a less sensitive crop is also an alternative when dealing with poor water quality. Some barley varieties can handle salinity similar to ocean water. Barley nets a grower $400 an acre, avocados $9,000 and $25,000 if the market is right for strawberries. Avocados are salt sensitive, so are strawberries and lemons and cherimoyas and star fruit and blueberries and raspberries and mandarins and nursery crops. We grow these because with our climate, very few other places can grow them and they return enough money for a grower to stay in business in an area where land, water and labor are expensive. We really don't have much in "alternative crops" to grow here.
avocado fruit
Water Quality Terminology
Along with drought there are also concerns about water quality which has all kinds of weird units that area actually convertible. Here's a little guide for the principle water quality components and their conversions.
Water Terminology
Common ions in water: calcium (Ca2+), magnesium (Mg2+), sodium (Na1+)
sulfate (SO42-), chloride (Cl-), carbonate (CO32-), bicarbonate (HCO3-), boron (H3BO3)
Measured as parts per million (ppm) or milligrams per liter (mg/l), which are interchangeable , or milliequivalents per liter (meq/l). A milliequivalent is the ppm of that ion divided by its atomic weight per charge.
Example: Ca2+ with atomic weight of 40 and a solution concentration of possibly 200 ppm. Ca2+ has two charges per atom, so it has a weight of 20 per charge. 200 ppm divided by 20 = 10 meq of calcium for a liter of water.
Total Dissolved Solids (TDS): measure of total salts in solution in ppm or mg/L
Electrical Conductivity (EC): similar to TDS but analyzed differently.
Units: deciSiemens/meter(dS/m)=millimhos/centimeter (mmhos/cm)=
1000 micromhos/cm (umhos/cm).
ConversionTDSEC: 640 ppm=1 dS/m= 1 mmhos/cm=1000 umhos/cm
Hardness: measure of calcium and magnesium in water expressed as ppm CaCO3
pH: measure of how acid or base the solution
Alkalinity: measure of the amount of carbonate and bicarbonate controlling the pH, expressed as ppm CaCO3.
Sodium Adsorption Ratio (SAR): describes the relative sodium hazard of water
SAR= (Na)/((Ca+Mg)/2)1/2, all units in meq/l
1.5 feet of water with EC of 1.6 adds 10,000 # of salt per acre
and that same water with 20 mg/l of nutrient will supply 80# of that nutrient/acre
Sea water has ~ 50 dS/m, 20,000 ppm Cl, 10,000 ppm
Irrigation water WATCH OUT- 1,000 ppm TDS, 100 ppm Na/Cl, 1 ppm B
avocado water