Fire Blight

Fire blight is the most damaging bacterial disease that affects shrubs and trees in the Rosaceous family during warm spring weather combined with rains or heavy dews.

This disease is most often found in pear, apple, loquat and crabapple trees and has become a nuisance to homeowners and commercial landscape managers. Flower infections can be introduced by bees and other insects from infected wood cankers that ooze bacterial substance in the spring. Trees infected with the fire blight bacterium Erwinia amylovora often have extensive limb cankers and dieback with a characteristic “Shepherd’s Crook” appearance at the tips of the shoots.

Anthracnose

In the spring, spores are transported to new buds and shoots. The disease is enhanced by cool, wet conditions. Infected leaves develop tan to reddish brown lesions that extend along the veins of the leaf. Considerable defoliation, sometimes with complete leaf loss, occurs on many trees by late spring in cool, wet years.

Different species of anthracnose impact a variety of tree species, including oak, ash, maple, elm, hickory, walnut, birch, linden, sycamore and dogwood. Sycamore, white oak and dogwood are particularly susceptible to anthracnose.

Phytophthora

Phytophthora is a genus of oomycetes that are similar to fungi. There are 59 species of Phytophthora, all of which cause disease in plants.

Phytophthora ramorum is the species responsible for Sudden Oak Death. Phytophthora are natural and universally occurring soil organisms which attack roots in poorly drained or anaerobic soils. As infected roots discolor and decay, the result is wilt, canopy dieback, cankers on the trunk, general decline and death. Phytophthora species are host specific attacking many types of trees including ash, cherry, pine, spruce, hemlock, fir, pear and dogwood

Sudden Oak Death

Sudden oak death (SOD) is the common name for a fatal tree disease caused by Phytophthora ramorum, a species of oomycetes that are similar to fungi.

SOD is one of 59 species of Phytophthora, all of which cause disease in plants. Many Phytophthora species attack roots in poorly drained or anaerobic soils. The primary hosts are coast live oak, California black oak, Shreve oak, tan oak, and canyon live oak. Many more cultivated species are likely susceptible to P. ramorum. Symptoms in other species are often expressed as leaf blight. P. ramorum can cause foliar disease in Douglas-fir, coast redwood and California bay laurel. Unlike many Phytophthora species that infect roots, P. ramorum is mainly a foliar pathogen

Lethal Bronzing

Lethal Bronzing (also known as Texas Phoenix Palm Decline) is caused by Phytoplasma palmae (a mollicute similar to bacteria, but lacking a cell wall) that is closely related to Palm Lethal Yellowing . Lethal Bronzing was first described in 1980 in Texas, and first reported in Hillsborough County, FL in 2006. Since 2006, it has spread throughout Florida, mostly around the central part of the state. The specific vector of Lethal Bronzing is unknown. Lethal Bronzing is most likely vectored by piercing-sucking insects that are known to spread phytoplasmas to plants. Phytoplasmas infect the phloem, the vascular tissue that moves carbohydrates from leaves to the roots.

As its former name implies, Lethal Bronzing infects Phoenix species. In Texas, the disease was reported to kill Phoenix canariensis (Canary Island date palm) and P. dactylifera (date palm) in as little as 4 months. Currently there are 10 confirmed hosts of Lethal Bronzing. In Florida, host range includes Phoenix sylvestris (Sylvester palm), P. canariensis, P. dactylifera, P. roebelinii (pygmy date palm), Sabal palmetto (sabal palm), Syagrus romanzoffiana (queen palm), Adonidia merrillii (Christmas palm), Bismarckia nobilis (Bismark palm), Livistona chinensis (Chinese fan palm), and Carpentaria acuminata (Carpentaria palm) (Bahder, 2017).

Bacterial leaf scorch

Bacterial leaf scorch (BLS) is a systemic disease caused by the bacterium Xylella fastidiosa, which invades the xylem (water and nutrient conducting tissues) of susceptible trees. Xylem-feeding leafhoppers/sharpshooters, treehoppers, and spittlebugs spread the bacterium from tree to tree. Transmission between trees through root grafts has also been reported. There is no cure for this disease; it is chronic and potentially fatal.

Beech Leaf Disease

Beech Leaf Disease (BLD) is a new disease of beech trees (Fagus spp.) that has been identified and observed in forest areas in Eastern USA and Canada. The cause of this disease remains to be confirmed, but a nematode species, Litylenchus crenatae n. sp., newly described from Japan on Japanese beech, is suspected to be involved in BLD.

Oak Wilt

Oak Wilt is a disease caused by the fungus Bretiziella fagacearum that is specific to oaks (Quercus spp.).

The fungus is spread through root grafts between neighboring trees and by insects. Red Oaks are particularly susceptible to oak wilt. The infection causes leaf discoloration, defoliation and death in a very short period of time (from two months to one year). Fungal mats will form under the bark and force outwards, cracking the bark of the tree. White oaks are more tolerant of oak wilt infection. Fungal mats will not form and it will take much longer for the tree to succumb to the disease. White oaks will show infected annual rings when viewed in cross section.