How to treat Xylella Fastidiosa from your Trees

Xylella fastidiosa is a species of pathogen which causes the disease called xylem-fluor (XF) or "acute oak decline." The disease affects plants belonging to the plant family called Oleaceae. It has been found in Italy, France, and Spain. XF impacts acorns, maple trees, laurel trees, oaks, privets, sycamores, crape myrtles, red maples, and certain other plants. The best method for treating xylem-fluor is control by way of quarantine.

Once the tree get infested, there are few methods known to treat Xylella Fastidiosa. However, prevention can be done by ensuring that your trees are healthy and not stressed. The best way to keep them healthy is through proper watering, fertilization, and pest control. It can also be managed by planting resistant varieties of Oleaceae.

One method for treating xylem-fluor is by using antibiotics directly applied to the tree. Neosporin (with pain relief) has been commonly used in Italy, France, and Spain with some success. The antibiotic Baytril may also be used for this purpose.

The method which seems to have the most promise though is called bacteriophage treatment, developed in Australia. They are genetically engineered versions of viruses that infect bacteria, so they kill Xylella fastidiosa. They are called bacteriophages because they attack bacteria , and thus apparently Xylella fastidiosa as well.

There is yet another method which has had some success, called solarization. This is where you can clear trees of infectious organisms by exposing them to sunlight for a long period of time. It may take up to six months for this method to be successful. You must place damp material over the soil or it will dry out too quickly, but if done right, it works very well.

Pest Management - A Silver Bullet?

If not controlled, Xylella Fastidiosa has the ability to kill plants by inhibiting fluid flow in xylem tissue (tubes) in plants. Xylem tissue makes up most of the transport system which moves water from roots to shoots. It also transports nutrients, sugars, hormones, and other substances throughout the plant.

The xylem cells are alive at maturity, even though they do not have nuclei or ribosomes, so it is not considered a type of non-living tissue. Water pressure provides the force needed for long-distance transport through these tubes.

Xylem-fluor disease is spread through propagation material (seeds), grafting stock, surface waters (such as rainfall, wash off from irrigation ), pruning tools, human activity (shaking trees), insects , and root grafts. However, some experts believe that Xylella fastidiosa enters the plant through wounds, root grafts , or insect activity.

Once in a plant, xylem-fluor moves rapidly within the xylem tissue, killing cells and causing leaf scorch symptoms. Thus far, there are no resistant cultivars. Soil solarization has been shown to be an effective method for eradicating it in several different crops. Active ingredients which have been successful include cinnamaldehyde, methiocarb, propiconazole, thiourea dioxide, dodine, copper oxychloride, chlorothalonil, penconazole, fluquinconazole, cyprodinil + fludioxonil mixtures, etridiazole, and mancozeb.

If you think your tree may be infected with Xylella Fastidiosa, contact a qualified arborist or state extension service for help. Early detection is key to saving your tree. Arborists can perform a number of tests to determine whether or not your tree is infected and, if it is, recommend the best course of treatment. There are many options for treating Xylella Fastidiosa- from deep root injections of antibiotics to removing the entire canopy of the tree- so don’t hesitate to reach out for help. We hope this article has been helpful in raising awareness about this devastating disease and providing some resources for those who need them.