David Doll0 commentsMay 8, 2015General

2015 Mid-Spring Updates

A lot of excitement this past week with the passing storms. Some large thunderstorms passed through Merced Co. dropping some hail and rain. As with any thunderstorms, rainfall totals vary. A few calls have yielded some concerns which are highlighted below. 1. Irrigation for areas with low rainfall totals will most likely still be needed. Use is highly variable depending on the weather, but for the most part, a warm (>80F) sunny day will require 0.25″ of water/acre to maintain full irrigation for a mature block. Cloud cover and cooler temperatures can reduce demand by as much as 1/2. This is using an assumed Kc value of 1.00. 2. Ants. Fields should be scouted and, if needed, baits should be applied. Baits – since they are growth regulators- must be applied 1 month prior to harvest for maximum effectiveness.  Be mindful that not all ants present within the orchard feed on almonds. A quick trick to distinguish “good ants” from “bad ants” is to throw potato chips or a hot dog near the mound. If consumed, it can be assumed that the colony will also feed on almond kernels. Another trick is to  stomp near the mound to bring ants to the surface. If they swarm out of the mound, are red in color with a black butt and bite, they are mostly likely fire ants. Monitoring and treatment information can be found on this previous post and at the UC IPM Website . Ants often cause more damage than expected. High populations can consume between 1-2% of the crop within four days. 3. Hail damage. Hail can cause crop loss as it knocks nuts and new growth form the trees. Nuts that are “bruised” may fall 3-5 days after the damage occurred. If the nut remains on the tree, it will typically yield

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David Doll8 CommentsSeptember 20, 2010Salinity

Water analysis and applying a leaching fraction for saline conditions

Written by: David Doll (UCCE Merced) and Daniel Sonke (Sureharvest, Inc). As discussed previously, sodium and chloride build-up in soils can cause crop loss by stunting plant growth. While much of the Central Valley has access to high quality surface irrigation water through irrigation districts, many almond orchards around the state have irrigation sources of variable quality. The first step in managing salinity is to know the source of salts. Water sources should be analyzed to determine the suitability for irrigation. Measurements of electrical conductivity (EC), sodium, calcium, and magnesium concentrations (cations), chloride, carbonate, bicarbonate, and sulfate concentrations (anions), pH, boron, and nitrate-nitrogen should be made. Most of these are standard.  Testing should occur on a regular basis since aquifer quality can change over time. Once the data is received from the test, the data should be checked for accuracy. First, the combined totals of all of the cations and the combined totals of all of the anions should be equal. Exclude boron and nitrate-nitrogen from these calculations. Next, if the EC is 5 dS/m or less, check to see if the sum of the cations is equal to 10 times the value of the EC. If these numbers are close, but not exact, the test is of good quality with all measurements made. If the EC and sum of cations are equal, most likely one of the cations/anions were estimated by subtraction rather than direct measurement. In the case of questionable quality, re-run the sample. Waters with ECs between 5 and 20 dS/m should use a multiplication factor of 12 instead of 10. Guidelines for water quality have been established to help identify excess salinity in water supplies. Estimating a 15% leaching fraction and the use of peach rootstocks (Nemaguard), the following table should be used as a guide to evaluate waters for suitable for irrigation

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