Cherry X Disease
They are specialized bacteria, characterized by their lack of a cell wall, often transmitted through insects, and are responsible for large losses in crops, fruit trees, and ornamentals.
[1] The phytoplasma causing Cherry X disease has a fairly limited host range mostly of stone fruit trees.
Most commonly the pathogen is introduced into economical fruit orchards from wild choke cherry and herbaceous weed hosts.
Rootstocks of Mahaleb cherry exhibit different symptoms from stocks of Colt, Mazzard, or Stockton Morello.
If it is x-disease the wood at the union will have grooves and pits this causes a browning of the phloem and shows the cells in decline.
This rapid decline is caused by the rootstock cells near the graft union dying in large quantities.
Trees infected with Mahaleb rootstock die by late summer or early the following year.
[citation needed] When Cherries are grafted onto Colt, Mazzard, or Stockton Morello rootstocks, there is a different range of symptoms.
Fruit on branches are smaller, lighter, pointed, low sugar content, poor flavor, and a bitter taste.
[5] The mountain leafhopper (Colladonus montanus) overwinters on winter annual weeds, particularly near streams and canals.
Adults can be plentiful on sugarbeet during late winter/spring and migrate to favored weed hosts such as curly dock or burclovers in orchards.
Depending on temperature and the vector, the average latent period for the cherry x disease is about a month or longer.
July through October is when the highest concentrations of pathogen are present in leaves of infected trees.
In high cherry producing areas, such as California, Washington, and Oregon, this disease could be devastating if left unchecked.
[6] If, in 2002, this disease was allowed to incubate, the results would show a drastic decline of production and huge loss of revenue as early as 2003.
This disease does not take long to develop and since fatality is always the endgame, high producing areas such as these would see results of epidemic proportions.
[citation needed] Leafhoppers are the only known vectors that can carry the X-disease from a wild host into peach and cherry orchards.
Other possible leafhopper vectors are Scaphytopius aculus, Paraphlepsius irroratus, Colladonus clitellarius and Norvellina seminude.
In late winter or spring, adults can be found in sugar beet fields and can then migrate to favored weed hosts (curly dock, burclovers) in orchards.
Occasional hosts are almond, apple and crabapple, apricot, bitter cherry, ceanothus, chokecherry, hawthorn, peach, pear, Japanese plum, and prune.
This is to maximize the effort at controlling both types of leafhoppers (Cherry and Mountain), thus cutting down the starting inoculum at both stages in the life cycle.
There exists a common herbaceous host, curly dock, which serves as the mountain leafhopper's main breeding ground.
