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 Doll0 commentsMay 4, 2012Insects

Considerations For Managing Ants In Almonds

Walter J. Bentley, Regional IPM Entomologist UC Kearney Agricultural Research and Extension Center Ant damage to almonds continues to be a difficult problem for farmers to manage.  In all areas of the state populations of the three species of ants which cause damage appear to be increasing.  From Fresno County going south to Kern County the California fire ant (also called the southern fire ant), Solenopsis xyloni, is the damaging species.  Another, less common species, is the thief ant, Solenopsis molesta, which is slightly smaller than Xyloni.  In Merced, Stanislaus, and San Joaquin Counties both the California fire ant and the pavement ant Tetramorium caespitum  can be found causing damage.  In the Sacramento Valley the pavement ant is the predominant species.  Although almond farmers will know, from past history of damage, whether or not they have a problem species in the orchard, there are other species that are considered more beneficial than harmful.  These include the bicolored pyramid ant, Doriomyrma bicolorand the native gray ant, Formica aerata.  This latter species has been found to actively feed on peach twig borer in unsprayed peach orchards.  The best way to separate the damaging species from those not causing damage is by examining the thin waist between the last pair of legs and the abdomen (stomach).  Both the pavement and the California fire ant possess two bumps or nodes while the beneficial species have only one node.  Also, the damaging species will often be found with weeds growing within the nest and are easily excited by disturbing the soil near their nests.  Finally, the pavement, California fire ant, and thief ant will aggressively bite and sting.  The California fire ant sting, in particular, is quite painful. While control information has applied to all three damaging species, monitoring methods and thresholds where only developed

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David Doll1 CommentMay 2, 2010Insects

Managing Orchard Ants – time to scout for activity!

Pavement and Fire ants can cause significant damage to the almond crop. Feeding throughout the year on seeds of grasses and broadleaves, ants are only problematic once the almonds are shaken to the ground. Ants can completely hollow out the nut, leaving only the pellicle behind. Damage increases the longer the almonds are on the ground. Within the San Joaquin Valley, the southern fire ant has a wider distribution and usually causes more damage than the pavement ant. Pavement ants are found in the northern San Joaquin Valley and into the Sacramento Valley. Within Merced County, we have both the Southern Fire Ant and the Pavement Ant. Recently, Merced County has had infestations of the Red Imported Fire Ant (RIFA), a third problematic ant for almond growers, requiring quarantine actions to control this invasive pest. Please see Guide to Identifying Orchard Ants to help identify ants. Ants tend to be problematic on drip or sprinkler irrigated orchards. Within flood irrigated blocks, ants are limited to tree berms. Moist, cool temperatures increase above ground activity of ants; hot temperatures drive the ants deeper into the colony. Varieties with a tight shell seal are more resistant to ant damage, or with shell splits less than 0.03 inches wide. Shell seal can vary greatly year to year depending on crop load, nut size, and horticultural practices. The orchard should be surveyed for ant colonies 2-3 days after an irrigation in the months of April – May in order to determine if a treatment is needed. Once the temperatures increase, problematic ant surface activity decreases, giving an inaccurate count of the population. In scouting for ants to determine if treatment is necessary, choose five survey areas per orchard, each about 1000 sq. ft., including the soil area from mid-alley to mid-alley beneath trees. Count the number

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David Doll0 commentsAugust 11, 2009Horticulture

Preparing for Harvest

It looks as if harvesting will be underway for Merced County within the next week to 10 days, with the date occurring earlier for growers on the West and South Sides of the county. With harvest, there are many preparations that must be taken into consideration. Water Management:In order to determine the last pre-harvest irrigation, a target harvest date must be set. Approximately two weeks after the last irrigation are required to “dry down” the trees enough to minimize bark damage from shaking. This time period does vary upon soil textures, with sand and clay requiring less and more time, respectively. This depletion of soil moisture tightens the bark to the trunk and prevents damage from the shaker attachment. Also, as the season progresses, the bark adheres tighter to the trunk. Therefore, with an earlier harvest, the chances of shaker damage are increased. In soils of low water holding capacity (i.e. sand) it may be necessary to irrigate between the harvesting of the varieties. Proper water management between varieties is just as critical as water management before harvest because during this period the tree is developing the fruit bud for the coming season. Any moderate to severe water stress during this period will reduce the formation of fruit bud. Timing of Harvest:Harvest timing should be considered using the following criteria: – The need to avoid naval orange worm damage to nuts on the tree and ant damage once nuts are on the ground; – The ability to achieve maximal nut removal; – The ability to maintain yield and quantity; – Minimization of tree injury; – Availability of harvest equipment; – weather conditions that may cause crop loss or damage (i.e. rain). A few of these points are highlighted below: Damage caused by Navel Orange Worm and Ants:Early harvest prevents the

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