Pest and Disease Tips For Fruit Trees

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CODLING MOTH (Apple and Pear): The first codling moth adults were caught in Willard, Perry, and Brigham City (Box Elder Co.) on May 1, in West Mountain (Utah Co.) on May 4, and in River Heights (Cache Co.) on May 5.

These catch dates correspond to 192, 219, and 138 DDs since March 1, for the three sites respectively. The catch in Cache Co. was unusually early based on DDs and tree phenology. First catch in Box Elder and Utah Counties is within the normal range of DD accumulation for biofix (200-250 DD). Biofix is expected at anytime in all locations in Northern Utah. Thank you to all who have sent in biofix information!

Codling Moth Control: Most insecticides function as larvicides, which means the insecticide kills the codling moth larvae following egg-hatch (and hopefully before they enter the fruit).

Remember to buffer spray water where necessary and follow the label directions closely. Uniform coverage is crucial. Tank-mixing 1% (or less) of oil will likely increase the efficacy of most materials.

Homeowners can use a 1% oil spray (such as SunSpray Ultra-Fine) with esfenvalerate (Ortho Bug B Gon), carbaryl (Sevin), malathion, spinosad (Ferti-lome formulation), permethrin, Codling moth virus (Cyd-X, Virusoft, Carpovirusine), pyrethrin, pyrethrum, azadirachtin (AZA-Direct), or Bt (Dipel, Thuricide).

Bagging fruit to keep larvae out after fruit is at least 1.5 inches in diameter and placing cardboard bands around trunks to trap cocooning larvae can also suppress injury.

In terms of DDs, another critical benchmark for codling moth is 340 DDs.? This is the point at which egg-hatch (larval emergence) accelerates tremendously. Approximately 70% of the 1st generation can be expected to hatch within the 340-640 DD period. This relatively short 320 DD window of time will see the greatest amount of pest pressure.

Multiple applications may be necessary for the 1st generation, depending on the severity of the codling moth infestation.

PEACH TWIG BORER (Peach, Nectarine, and Apricot): It is time to put out peach twig borer pheromone traps in the warmer locations in northern Utah. First peach twig borer moths are expected 10-14 days after codling moth, about 400 DD after March 1.

WESTERN CHERRY FRUIT FLY (Sweet and tart cherry): It is approaching time to put out cherry fruit fly traps: 700 DDs.? First flies are expected about 900 DDs. Yellow sticky traps for fruit fly should be placed in cherry orchards in the next 1-2 weeks in northern Utah.

PLUM CURCULIO (All tree fruits): Plum curculio is a state quarantine insect pest that has only been found in Box Elder County. The first plum curculio adults of the season were found in traps in Perry and Brigham City on April 24. Traps for regulatory concerns should be placed in other northern Utah counties now.

*********Disease Advisory*********

FIRE BLIGHT: As long as apple and pear trees are in bloom, blossom infections by fire blight bacteria are a concern. Be on the watch for oozing cankers. These cankers should be removed by pruning out the disease at least 18-22 inches back from the actively oozing canker. Special care should be taken to remove the diseased wood and burn it or remove it to a waste disposal area that will be buried.

Removal of an infected tree may be warranted if a canker occurs on or very near the main trunk. Special care should be taken to wash the pruning tools between each cut when working around active fire blight.

A 10 percent solution of household bleach can be used or even by spraying pruning tools with Lysol between each cut. Be sure to wash hands if a person comes into contact with the bacterial ooze prior to handling branches/limbs of other uninfected trees. If one must use chemicals to control the disease there are two agricultural antibiotics, streptomycin and tetracycline, that may be used to spray apples or pears during the blooming period.

These chemicals are not usually needed in the home fruit orchard if homeowners keep watch for new fire blight infections (rapid wilt and shepherds crooking at the end of affected shoots) and promptly remove them by pruning the disease out before it spreads to neighbors or commercial orchards nearby.

APPLE POWDERY MILDEW: Apple powdery mildew over winters in the flower buds and infections have been heavy in some locations this year. Maintain a vigilant mildew control program.

CORYNEUM BLIGHT: Spring 2006 is shaping up much like the Spring of 2005, a prolonged wet and cool season just right for Coryneum blight. This is a disease that can be actively growing on stone fruits (almonds, peaches, nectarines, and cherry) in very cold weather when you might be thinking it is too cold for any disease to get going. Depending on where you are, your peaches may be blooming or approaching petal fall soon. Chemical control recommendations for the blossom time of crop development include Captan, Thiram Granuflo and wettable sulfur.