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.

'Nonpareil' kernels almost completely filled. Photo taken May 4th near Los Banos, CA
"Nonpareil" kernels almost completely filled. Photo taken May 4th near Los Banos, CA

  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 a marketable nut. Several people have asked if they should spray a fungicide to protect the damage nut. Generally, this is not advised.
  4. Crop Development is ahead of last year, and several weeks ahead of normal. Kernel fill is nearing completion in Nonpareils within Merced County, and may be completed in other areas. Plan nitrogen, irrigation, hull-split sprays accordingly.
  5. Sampling of well and canal water. A lot of orchard blocks and irrigation districts are relying on ground water for irrigation. A water sample needs to be submitted for analysis to determine the salt load within this water. Water quality can degrade as the season progresses. Water within canals can also change as decrease snowpack and river flows reduce the amount of clean water. Sample frequently if managing a salinity problem and adjust the leaching fraction as appropriate.