Boxwood | Texas Plant Disease Handbook

Buxus spp.

Phytopthora Root and Crown Rot

Fungal pathogen	Phytophthora cinnamomi and Phytophthora parasitica
Area(s) affected	Roots and crown
Signs/Symptoms	Foliage will have an off-color, appearing tan and dried- out. As the disease progresses, individual sections of the canopy will brown. Roots turn dark brown and lower stem and crown tissue turn dull gray to brown. If root and crown rot are severe, plant death will occur.
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Root Knot Nematode

Pathogen	Meloidogyne spp.
Area(s) affected	Roots
Signs/Symptoms	Feed on the inside of the roots inducing knots or galls on them. These swellings are usually white and round to irregularly elongated. Foliage may wilt, appear stunted, and turn yellow to bronze.
For more information	http://www.apsnet.org/edcenter/intropp/lessons/Nematodes/Pages/RootknotNematode.aspx

Ectoparsitic Nematodes

Pathogen	Ring, Stubby Root, and Stunt
Area(s) affected	Roots
Signs/Symptoms	Feed on root tips causing foliage to wilt, appear stunted and turn yellow to bronze.
For more information	http://plantpath.caes.uga.edu/extension/nematodes/ring.html http://plantpath.caes.uga.edu/extension/nematodes/stubbyroot.html

Lesion Nematode

Pathogen	Pratylenchus spp.
Area(s) affected	Roots
Signs/Symptoms	Feed on both the outside and inside of roots causing darkened areas of dead tissue along the root as they move and feed. Foliage may wilt, appear stunted, and turn orange or bronze.
For more information	https://www.apsnet.org/edcenter/intropp/lessons/Nematodes/Pages/LesionNematode.aspx

Decline, Dieback, Root Rots, Twig Blight, Cankers

Fungal pathogens	Armillaria spp., Fusarium spp., Gandoderma spp., Nectria spp., Phymatotrichum spp., Rhizoctonia spp.
Area(s) affected
Signs/Symptoms	Infected branches often start growth later in spring than normal ones. Leaves on such branches usually curl upward close to the stem and turn light grayish-green or bronze and finally straw-colored. Leaves may wither and drop early leaving bare twigs. Roots may be decayed. The bark at base of branches may die and slough off.
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Leaf Spots, Leaf Tip Blights, Leaf Cast

Fungal pathogen	Diplodia spp., Phoma spp., Phyllosticta spp.
Area(s) affected	Leaves
Signs/Symptoms	Leaves variously spotted may become pale or straw-colored, sometimes dull tan or brown, starting at margins and tips. Many leaves drop early. Young twigs may die.
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Winter Injury

Causal agent	Freezing temperatures
Area(s) affected	Entire plant
Signs/Symptoms	Leaves may turn bronze, rusty brown or red with dead areas around the margins. Leaves, twigs and even entire plants may die back.
For more information	http://www.mobot.org/gardeninghelp/plantfinder/hortline.asp?code=3959

For additional support and current disease management information, contact your local AgriLife Extension Office: http://counties.agrilife.org/

Content editor: Corinne Rhodes, Undergraduate Extension Assistant, Texas Plant Disease Diagnostic Laboratory. This project was performed to satisfy BESC485 requirement under the supervision of Dr. Kevin Ong, kevo@tamu.edu, Director, Texas Plant Disease Diagnostic Laboratory, Texas A&M University, Texas AgriLife Extension Service (April 25, 2014)