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Insect and Disease Pests In Delaware’s Forests. Envirothon Training. Symptoms vs. Signs. Symptoms Changes in the plant’s appearance that indicate something is happening. Ex: crown dieback, wilting, cankers. Signs - PowerPoint PPT Presentation
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ENVIROTHON TRAINING
INSECT AND DISEASE PESTS
IN DELAWARE’S FORESTS
SYMPTOMS VS. SIGNS
• Symptoms• Changes in the
plant’s appearance that indicate something is happening. Ex: crown dieback, wilting, cankers.
• Signs• Indications of
the insect or disease itself. Ex: frass, pitch tubes, fungal fruiting bodies.
THE ENVIROTHON SEVEN!
• Know these:1. Emerald Ash Borer2. Asian Longhorned
Beetle3. Southern Pine
Beetle4. Gypsy Moth5. Sirex Wood Wasp6. Bacterial Leaf
Scorch7. Sudden Oak Death
• For each, know:
1. Native/non-native2. Present in
Delaware?3. Host species4. Symptoms & Signs5. Type of damage6. Control measures
INSECTS
EMERALD ASH BORER (EAB)
• Non-native• Has not been found in Delaware, but present in
Maryland• A threat to ash trees only• Larvae create galleries in the cambium of infested
trees, girdling the trees
Adults are bright green and easy to identify.
EMERALD ASH BORER
(EAB)
Galleries D-shaped exit hole, splitting bark
Crown dieback
Woodpeckers feeding
EMERALD ASH BORER (EAB)
•Control in our area = ERADICATION
(Remember, it has not been detected yet in Delaware)
•Cut all ash trees in the area of new infestations. Chip the trunks and branches to a small size.
ASIAN LONGHORNED BEETLE (ALB)
• From China• Has been detected in New York, New Jersey, not
DE• Threatens numerous types of trees, particularly
the maples.
ASIAN LONGHORNED BEETLE (ALB)
• The beetle develops within the xylem (wood) and then bores its way out. Eventually the many exit holes will destroy the cambium and kill the tree. The weakened wood can also cause structural failure (tree breaks in half).
ASIAN LONGHORNED BEETLE (ALB)
• Large exit holes are conspicuous signs of ALB infestation.
ASIAN LONGHORNED BEETLE (ALB)
Infested trees must be removed,
and chipped to destroy all beetles.
ASIAN LONGHORNED BEETLE (ALB)
Packing materials are inspected at ports of entry.
SOUTHERN PINE BEETLE (SPB)
• Native• Present mainly in southern
DE• Hosts are hard pines (all
except white pine)• Chews galleries which can
girdle trees. Also introduces a harmful fungus.
• Delaware is at the northern end of its range. A more serious pest in the South.
SOUTHERN PINE BEETLE (SPB)• Infested stands
can be detected with aerial surveys. Infested pines display brown foliage.
SOUTHERN PINE BEETLE (SPB)
Small round holes
S-shapedgalleriesPitch tube
SOUTHERN PINE BEETLE (SPB)
Infested trees can be cut and burned, chipped, or sprayed.
Control
GYPSY MOTH• Non-native• Introduced into
Massachusetts in 1869. Since then it has spread throughout the northeast, including Delaware.
GYPSY MOTH
• Larvae feed on the leaves of many broadleaved species, particularly the oaks.• Host trees are
damaged through defoliation.
GYPSY MOTH
• When severe defoliation occurs several years in a row, widespread mortality can result.
GYPSY MOTH
Defoliation can be seen from the air during June survey flights
Egg masses
GYPSY MOTH• Egg masses are easily seen in the fall. These
methods can determine the need for a control program the following spring.• Control = chemical sprays.
• Non-native• Has not been found in Delaware• Threatens loblolly and other pines• Forms galleries that injure trees• Carries a fungus that causes more damage
Sirex Wood Wasp
Sirex Wood Wasp
Round exit holes
Resin beads
Symptoms / Signs
Wilting and discoloration
Sirex Wood WaspControl
• Control measures unknown (new pest)• Biological controls have been successful in other parts of the world• Early detection surveys in DE using trap trees
Red pine trap tree at White
Clay Creek SP
DISEASES
Control:• Native to the United States• Present throughout Delaware• Hosts = red oaks and other trees
• Mainly northern red, pin, black, and scarlet oaks• Symptoms = Marginal leaf scorching in late summer and fall, dieback
Bacterial Leaf Scorch (BLS)
• The bacteria are spread (vectored) by insects that feed on the xylem• Bacteria reproduce and physically clog the xylem• Simply a “plumbing” problem. Not enough water can move through the xylem to branches and leaves, so living tissues dessicate and die.
Bacterial Leaf Scorch (BLS)
Bacteria clogging
xylem
SymptomsBacterial Leaf Scorch (BLS)
Marginal leaf scorch
Dieback
Control
Bacterial Leaf Scorch (BLS)
• No proven prevention• No proven cure• Treatment trials ongoing in Delaware and elsewhere• Do not plant northern red oak or pin oak
• Non-native• Has never been found in Delaware• Threatens oaks and other trees, as well as viburnums and other understory plants• Two types of symptoms:
Sudden Oak Death (SOD)
• Understory plants• Foliar scorching• Twig dieback
• Overstory trees• Bleeding stem cankers• Dieback
+
Understory plants
Dieback
Twig dieback
Foliar symptoms
Overstory Trees
Bleeding canker
Sudden Oak Death (SOD)
Control:• No control in generally infested areas such as California• Control in other areas is quick response after detection. Cut, pile, and burn is an accepted prescription in new detection areas.• Quarantines are in place to prevent new introductions.
Sudden Oak Death (SOD)
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