Pest and Disease Information

Cherry fruit fly

Cherry fruit fly attacks all varieties of cultivated and wild cherries. Maggots, which develop inside the cherries, make the fruit unmarketable. Poor control can have serious consequences since major markets for Northwest cherries, such as California and many foreign countries do not tolerate any infestation of packed cherries. 

Codling moth

The Codling moth originated in Asia Minor, but has been a principal pest of apple and pear in North America for more than 200 years.  They spend the winter as a mature larva in a cocoon, in litter at the base of the tree, in wood piles, on picking bins in the orchard or on farm buildings near packing sheds where culled apples might have been dumped. Damage is caused by feeding of the larvae in fruit. Deep entries occur when larvae bore to the center of the fruit and feed on seeds. Stings are shallow entries where the larvae died or gave up and tried another place. 

Apple maggot

Apple maggot is a native North American pest whose original host was hawthorn. The first confirmed apple maggot infestations in the Northwest were in Oregon in 1979. Since then, trapping programs have located maggots in western Washington and western Oregon. It is likely the maggot was introduced to the western United States by people transporting infested fruit from the eastern states.  The apple maggot, being very adaptable, can infest many different plants including apple, hawthorn, plum, apricot, pear, sweet cherry, sour cherry, wild rose, Cotoneaster sp. and Pyracantha sp. 

Little cherry virus (LChV)

Little cherry virus (LChV) causes trees to produce smaller than normal fruit. The fruit produced doesn’t ripen normally or taste as good. This virus spread rapidly across the fruit growing area of British Columbia almost destroying British Columbia’s cherry industry. LChV-1 and LChV-2 have been described from Oregon and Washington including a mixed infection of both viruses. 'Deacon', 'Lambert', and 'Sam' are most susceptible to little cherry disease but it also occurs in 'Bing' and 'Sweetheart.' 

Little cherry virus (LChV)

Little cherry virus (LChV) causes trees to produce smaller than normal fruit. The fruit produced doesn’t ripen normally or taste as good. This virus spread rapidly across the fruit growing area of British Columbia almost destroying British Columbia’s cherry industry. LChV-1 and LChV-2 have been described from Oregon and Washington including a mixed infection of both viruses. 'Deacon', 'Lambert', and 'Sam' are most susceptible to little cherry disease but it also occurs in 'Bing' and 'Sweetheart.' 

Pear Psylla

The pear psylla, (pronounced sil-la), is the primary pear pest in North America. It was accidentally introduced into Connecticut in about 1832 and remained an Eastern pest until it was found in the Spokane Valley of Washington State in 1939. The psylla has since spread to all the pear growing areas of the United States and Canada.

Fire Blight

Fire blight is an important disease effecting pear and apple. Infections commonly occur during bloom or on late blooms during the three weeks following petal fall. Increased acreage of highly susceptible apple varieties on highly susceptible rootstocks has increased the danger that infected blocks will suffer significant damage. In Washington, there have been minor outbreaks annually since 1991 and serious damage in about 5-10 percent of orchards in 1993, 1997, 1998, 2005, 2009, 2012, 2015, 2016, 2017, and 2018.