Replant Disease

 
When some trees and shrubs, particularly members of the family Rosaceae (roses, apples, cherries, pears and plums) are planted into soil in which the same species was previously growing, they may fail to thrive and even die. The subsequent above-ground symptoms of stunting and poor growth are, in fact, the result of poor root development. This problem has been known by several names, including 'replant disease', 'soil sickness', 'specific apple replant disease', or 'rose sickness.' The plants will often recover if they are moved to fresh soil

Cause- There is thought to be more than one cause of replant disease, but the general opinion is that during the life of the first planting, there is a significant build-up of root pests and diseases, such as nematodes and by pathogenic fungi. These increase gradually and do not reach high levels until the plants are well established, by which time the root systems are large and robust enough to withstand any adverse effects.

The pathogens therefore have no effect on the vigor of the initial planting. However, when the original plants are removed, a high population of these harmful organisms will remain in the soil in the root zone. When new, young replants with only small root systems are planted in this 'contaminated' soil, they struggle to cope. Evidence for this theory is not conclusive, but is based on:

• Detection of high levels of damaging fungi and nematodes on some affected sites.
• Removal of the problem by soil sterilization.
• Amelioration of the problem in some cases by the use of additional fertilizer to promote rapid root growth.

Susceptible Plants- that are particularly prone to replant disease include apples, pears, plums on St Julien A rootstocks, peaches, cherries, roses (especially on some Rosa canina roostocks), quince and citrus.

Symptoms-  Roots are weak and may become blackened, plants grow poorly and may fail to establish

Prevention and Control-  Avoid  planting susceptible plants where the same or related plant has been recently removed. If you must replant in the same spot, dig out a large hole and  replace the old soil with fresh soil from a site where the susceptible plant has not been grown greatly reduces the probability of replant disease.

Guardian MY Liquid Beneficial Soil Fungi  contain Mycorrhizae which are beneficial soil fungi that colonize in and around the roots of plants. These colonies form a symbiotic relationship with the plants and increase the root mass by up to 1000 times, therefore, allowing the plant to uptake nutrients and water more efficiently.

Mycorrihzae also benefits plants by releasing chemicals that aid in dissolving elements like iron that are harder for plants to absorb.

Other benefits of mycorrhizal inoculation include improved soil structure due to the increased rhizobial activity, and increased disease and pathogen resistance which can be associated with the excretion of special antibiotics produced by Mycorrhizae.

Products for Preventing Replant Disease

Humega 8% Soil Conditioner  $25.50	Beneficial Fungi  $33.95	Mycor Transplant Tree Saver $4.29

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