Spring Insects and Diseases
Cicada
Spruce
Spider Mite (Acrobat PDF file)
Maple
Bladder Gall Mite (Acrobat PDF file)
Oystershell
Scale (Acrobat PDF file)
Introduced Pine Sawfly- Diprion Similis- The
sawfly has two generations. The sawfly has two generations and a partial third generation
in southern Indiana. The second generation usually produces the noticeable defoliation,
which means that you may not observe thin defoliated crowns until September and October in
plantations defoliated for the first time. For plantations defoliated this year you will
observe the thin defoliated crowns in April with the level of defoliation increasing
during June to July.
The larvae has a black head, a dark body, black stripes down the back and yellow and black spots on the sides. The first generation larvae will be present from mid-May through June. The second generation is present from late July through September. A third generation may be present in November. When larva are not present and during the winter, you can recognize their presence from the brown capsule-like pupal cases attached to needles and twigs of white pine or to twigs of understory shrubs and weeds.
The sawfly prefers white pine but also feeds on scotch, red, jack and mugho pine. The first generation feeds on older needles but second and third generations feed on current year and older needles. It is the multiple generations and feeding on all needles that can severely defoliate and stress the tree. Damage will be growth loss, increased stress making trees more susceptible to bark beetles and root rot and possible mortality in sawtimber size trees. Management decisions should be made with consideration of the overall management goal for the forest stand, the amount of past defoliation, an estimate of future defoliation level, the stand stocking level, an estimate of the tree and stand's current health (food or poor), and an estimate of damage (growth loss and mortality). For Christmas trees the loss of aesthetic quality from defoliation is the prime consideration when making a management decision. Management tools will include harvesting and thinning in forest stands and pesticides in Christmas tree and windbreak plantings. Pesticides available include Orthene, Sevin, Cygon, malathion and Dursban.
EUROPEAN PINE SAWFLY - Neodiprion sertifer - This
sawfly may be confused with the introduce Pine Sawfly (IPS) because both feed on older
needles of pines in the spring. But, there are several differences between the two
sawflies.
1.) EPS prefers to feed on scotch pine not white pine and will also feed on red, jack and mugho pines.
2.) EPS larva are yellowish green with black stripes down the back and a black head. They do not have the yellow spots that IPS larva have.
3.) EPS larvae will emerge a little earlier than IPS and should be present from late April through May and early June.
4.) EPS does not place its cocoons on the needles and twig.
5.) EPS has one generation per year and is not seen later in the summer like IPS.
6.) With one generation per year, EPS feeds only on older needles and does not feed on current year needles which IPS will do.
EPS is primarily a pest in Christmas tree plantations and windbreaks. It has not been a problem in forest plantations. In epidemic situations, EPS can severely damage the quality of Christmas trees and require pesticide application.
Generally, EPS is spotty in a plantation and can be easily managed by physically destroying the larvae that feed in colonies. Should pesticides be needed , Sevin, Cygon, Orthene, malathion or Dursban can be used.
LOOPER COMPLEX - Linden Looper, Erannis tiliaria & Half-Wing Geometer, Phigalia titea Linden looper is yellow with black lines down its' back and reddish brown head. The half-wing geometer is black with yellow spots on the side and hair or spines on each segment. Both move with an "Inching" movement and reach a length of 1-1.5".
Two other loopers (or "inchworms") may be observed spring and fall cankerworms. Fall cankerworm larva have color variation ranging from light green to dark brownish green. The light green larvae will have white longitudinal lines. The darker larvae will have a dark stripe down the back. Spring cankerworm larva are reddish to yellowish brown, yellowish green or black with a yellow strip on the side above the spiracles. The cankerworm larvae can be separated by the number of prolegs on the tail. Fall cankerworm has 3 pairs of prolegs with 1 pair vestigial (or very small), and spring cankerworm has 2 pairs of prolegs on the tail.
YELLOW POPLAR WEEVIL - Odontopus calceatus - The small black weevil, that some people thin is a tick, is active in April feeding on the expanding buds and leaves of yellow poplar, sassafras and magnolia. As the new leaves expand, the weevil chews "rice-shaped" holes in the leaf and lays eggs along the midrib. Larvae emerge and make a leaf mine between the upper and lower leaf surface. This leaf mine will turn into a reddish brown to black blotch on the leaf. It is the leaf mine and the "rice shaped" hole that gives the yellow poplar trees a rust red or "burned" appearance witch would be seen during late May through June.
There is only one generation per year, and the black weevil adults will move to the ground in July to pupate. Management measures are usually not needed for the forest or plantation trees unless they are seedlings. Ornamental trees may need pesticide treatment if the defoliation was heavy or the defoliated appearance is unacceptable to the landowner. Sevin or Dursban can be applied during budbreak. Application may also be made in July to kill emerging adults of the next generation and prevent defoliation.
PINE NEEDLE SCALE - Chionaspis pinifoliae and C. heterophyllae - The whitish to silvery white, or even chlorotic, scotch pine Christmas trees may be infested with this scale. The scale produces a white cover which is found on the needle. The population of this scale may be increasing in Christmas tree Plantations and ornamental plantings. However, the effect of the cold winter temperatures on egg survival is unknown and could reduce the damage and the scale.
The primary hosts for both species are scotch and mugho pine. They will feed on other pines species; but C. pinifoliae will feed on other conifer genus such as the spruces. Both have two generations per year, and their crawler stage of the first generation will be hatching in late April and early May. The second generation will hatch in July. The crawlers are young scales that move to a feeding site. They do not have the scale covering used to protect them which makes it easier for insecticides to control them. The crawlers are small reddish brown spots on the needles. A magnifying lens will help in recognizing them.
In Christmas tree plantations, pine needle scale occurs in spots of a few to many trees scattered across the fields. Therefore, when you find a heavily infested tree, the surrounding trees may also be infested but to a lesser degree. If insecticides are applied, it is best to treat several rows of trees around the heavily infested trees. April is the time to apply insecticide treatments against first generation crawlers. Orthene, Cigon, Diazinon, Dursban, Sevin and Malation can be used. Another consideration before treatment is the amount of predation from lady bird beetles. Scales that have holes in the "white" scale are prayed upon by the beetle. You may also observe the beetles. If predation is heavy, application of insecticides may not be needed depending on management goal of the Christmas tree grower.
WINTER BURN - The damage along roads may also be the result of salt spray. Symptoms are reddish brown needles usually on one side of the tree - the side of the tree facing the road or the south and southwest side. Symptoms will not occur or be greatly reduced on the north side and the side away from the road. Trees will be stunted and have thin foliage. Some will recover from the damage, but trees with years of repeated exposure, especially to salt spray, will eventually weaken and die. Generally, winter bum is more common in northern Indiana.
BAGWORM - Thyridopteryx ephemeraeformis - Many think of bagworm
as a pest of conifer trees such as Arborvitae, E. red cedar, white and scotch pine, and
Norway and blue spruce. However, bagworm will feed on many hardwoods such as oaks, maples,
black locust, sycamore, persimmon, elm and others.
Also, the name "bagworm" is used by many to refer to the tents of Eastern Tent Caterpillar that occur in black cherry at this time of the year. Or they are referring to the webs of Fall Webworm found at the end of branches of various hardwoods - black walnut, persimmon, black cherry, sycamore and other others - in the late summer.
Bagworm is the grayish brown silken case covered with needles or leaves approximately 2" long when fully grown. They firmly attach to the twigs of trees infested. The larva stay inside the bag while feeding, and it is only the male moth who emerges from the bag. The female stays in the bag and lays her eggs in the bag which overwinter.
The cold winter temperatures may have killed eggs in bags that were exposed. Bags inside infested trees may have had enough protection from the cold temperatures for eggs to survive. Egg hatch usually occurs in late May and early June. At this time insecticide treatments are the most effective. Once bags reach 1" in length, it is much harder to achieve control and prevent defoliation. Insecticides available are Dipel, Thuricide, Orthene, Cygon, Diazinon, Dursban or malathion. Another good control is hand removal and destruction of all bags, but this should only be recommended for individual ornamental trees.
White pine has been severely defoliated in previous years and had top dieback of the tree from feeding on the bark of twigs by early instar larvae. Carefully examine white pine for the small bags that will look like buds. Bagworm tends to attack the top whirls of the tree first. So examine this area when surveying for Bagworm.
EASTERN TENT CATERPILLAR - Malarosoma americanum - The white silken webs (tents)of ETC should be evident in the branch axils of black cherry saplings at this time.. Besides black cherry, ETC will also feed on ornamental fruit trees. With low populations, physical removal of the tent is one control measure to use. Removal should be done early in the morning or at dusk when the caterpillars are in the tent and when the tent is small. Insecticides such as Sevin can be used if needed. Caterpillars grow to 2.5" and are black with a white stripe bordered by brown stripes down it's back and blue mark along its' side. If defoliation does occur, feeding should be finished by late May or early June.
FOREST TENT CATERPILLAR - Malacosoma disstria -Forest Tent Caterpillar is the black hairy caterpillars with white "key-holed" shaped spots down its' back. They prefer to feed on sugar maple, white oak, black oak, red oak, other oaks and black cherry. Caterpillars are present from late April through May. They pupate in June and lay egg masses on twigs which overwinter. There is one generation per year.
ZIMMERMAN PINE MOTH - Dioryctria zimmermani - 
The overwintering larva are
leaving the resting cocoon and moving to shoots to bore into them around April. When they
bore into the shoot, a pitch mass of resin may form at the entrance hole. After feeding in
the shoot, they will move to the branch whirl and bore into it.. The pitch mass will also
be present at the whirl. Adult moths will emerge in July and August with the next
generation larva hatching in late August and early September. The larvae then move to the
bark cracks to overwinter.
Most of the activity will be in the upper or top whirls. The symptoms of an attack will be off colored branches ranging from chlorotic to reddish brown. Branch breakage also may occur. Heavily infested brood trees can be recognized by the excessive pitch masses at the branch whirls, and a larger diameter stem above a whirl than below it may also be present.
To manage Zimmerman pine moth, remove and destroy brood trees and consider the use of insecticides. Cygon, Mavrik, and Thiodan can be used. With larvae cmerging now to move to shoots to feed, insecticides should be applied in heavily infested fields. When the next generation larva appear in August-September, insecticides can be applied to help prevent damage for the next year.
Trees damaged by Zimmerman pine moth may serve as a breeding tree for Pine Shoot Beetle. Therefore good monitoring or your fields and sanitation will help to prevent damage from these pests. Zimmerman pine moth prefers scotch pine, but will also attack red, Austrian, and white pines.
NANTUCKET PINE TIPMOTH - Rhyacionia frustrana - Christmas tree growers in southern Indiana, especially in counties along the Ohio River, may not be looking for Zimmerman pine moth, but they may need to look for Nantucket pine tipmoth. Tipmoths overwinter as pupa in infested buds. They should be emerging around April for the first of two or three generations. Larvae feed at the base of needles and then move to the bud where they bore in and consume the inside of the bud. After feeding on buds, they will make a tunnel down the shoot.
To recognize tipmoth damage, look for reddish brown needle clusters at the end of the twig. Then move closer to the twig and look for a cream color resin pocket at the base of the buds. Also look for shepherd's crooks of the new shoots and dead shoots.
Tipmoth prefers scotch and shortleaf pine, but also will attack Virginia pine. To manage tipmoth, shearing can be used to help correct damage. Some control is achieved from shearing and leaving the shoots on the ground. Another tool to use is the pheromone trap for Nantucket pine tipmoth. The trap determines when moth flight has occurred, provides an estimate of population levels and gives better timing for application of an insecticide. Heavily infested Christmas tree plantations can be sprayed with Cygon, Orthene, Dimilin or Pounce.
DOGWOOD ANTHRACNOSE Discula destructive - In 1993,
dogwood anthracnose was found for the first time in Indiana. Initially found on flowering
dogwood on the Purdue Campus, dogwoods in St. Joseph, Elkhart, Allen, Vigo, Hamilton,
LaPorte, Johnson, and Clark counties were found infected. All reports of the disease were
identified and confirmed from spores by Gail Ruhl and Karen Rane at Purdue University's
Plant and Pest Diagnostic Lab. All trees infected were from the ornamental, residential or
nursery environment.
Leaf spot symptoms of dogwood anthracnose occur in May an June. The spot has a tan to brown center with a purple border and is medium to large. On the underside of the spot, small tan to brown specks may be seen. These are the fruiting bodies, of the fungus. Another leaf symptom is scorched tan blotches that eventually cover the entire leaf. Blighted leaves may cling to the twig after normal leaf drop in the fall.
Other symptoms to use at this time are dead branches and twigs with blighted leaves that may be clinging to them. Also epicormic sprouts may be present on the main stem. The blighted dead leaves may also be present on the sprouts. Examination and removal of the bark around a sprout or dead twig may reveal the canker that dogwood anthracnose eventually forms.
There is another leaf spot that infects dogwood and is similar to, dogwood anthracnose. It is not anthracnose, Elsinoe corni. This leaf spot is smaller in diameter than the leaf spot of dogwood anthracnose. However, if they are numerous on the leaf, they may merge to form larger spots.
Management is only recommended for ornamental trees. Prune out infected or dead twigs and branches during dry periods. Keep trees watered during droughts, but do not get the foliage wet. Fertilize trees with a low-nitrogen fertilizer as high nitrogen fertilizers will stimulate succulent growth. For high value trees, fungicides - Daconil, Zyban or Banner - can be applied from budbreak through mid-June.
SYCAMORE ANTHRACNOSE - Apiognomonia veneta -
The weather during the
last two weeks of April and first week of
May generally determine the intensity of this disease. If temperatures are in the 50's and
moderate to heavy rain occurs, defoliation to sycamore will be noticeable varying from
light to heavy. This will mean that sycamore will not develop full foliage until June. The
amount of damage will vary south to north in the state because of differences in weather.
Anthracnose infection occurs at budbreak and during leaf expansion. Besides defoliation, symptoms include a brown leaf blotch associated with the leaf veins. The disease moves from the leaf to the twig were it produces a canker and causes dieback. On heavily infected trees dieback can be extensive leading to the gradual decline and death of the tree. If the weather conditions occur to produce defoliation on sycamore, anthracnose symptoms also occur on oaks, ashes, and maples.
Sanitation - raising and destruction of fallen leaves and twigs - helps to prevent damage. Fungicide treatments are not generally recommended.
Yellow Poplar Decline - cause unknown - During the late 1980's, Ohio was reporting a decline of yellow poplar. At that time, no decline was reported in the forest of Indiana; however there was a dieback and sprouting of yellow poplar saplings in plantations across Indiana. This dieback had multiple cankers on the main stem that died down to the root collar. A cluster of sprouts then grew from the root collar.
Cankers occur along the length of the bole from the crown down to DBH. The cankers may be open showing the callus ridge and inner wood or closed with bark over the canker face. The declining trees occur in a group; however more sampling is needed to determine if grouping is a consistent symptom. More samples are needed to determine if there is an association with site, aspect, position on slope, crown position or other factors.
CYCLANEUSMA NEEDLECAST - Cyclaneusma minus -This needlecast has a long infection period from spring through the fall; however it is the spring infection time that is more important. Infection at this time of newly formed needles will not produce symptoms until they are second year needles. Also some infection of second year needles can occur this spring and produce symptoms this fall.
The yellowing of second year needles can occur throughout the growing season and some trees will hold chlorotic needles for a long time before cropping them. Usually it is the September to November period just before harvest when trees suddenly have their inner needles turn yellow and began to drop. Infected needles are yellow with brown transverse bands. Cream to tan colored fruiting bodies form in infected needles erupting through the needle surface and releasing spores when wet.
Christmas tree growers with this disease should consider fungicide treatments on trees within two years of harvest. Applications to younger trees is not recommended. Two to three applications of chlorothanil (Daconil or Bravo) should be made at this time. The flowable formulation is recommended over other formulations.
WHITE OAK "TATTERS" - The first flush of oak leaves, primarily white oak, can develop "tatters" symptoms. Tattered leaves have only the veins and a small amount of leaf tissue along the veins. The margin of the leaf tissue is irregular which helps to give the leaf a "tattered" appearance, as if the leaf was beaten against something to knock off the leaf tissue. The cause of this disease remains a mystery, but cold temperatures, frost, plant bugs, thrips and leaf hoppers are suspects.
Most observations of "tatters" have been in northern Indiana primarily to white oak, but burr, red, black and swamp white oaks have had the disease."Tatters" occurs to only the first flush of leaves, is heaviest in the lower part of the tree crown and occurs to random trees (not uniformly distributed to all trees).
PINE ROOT COLLAR WEEVIL - Hylobius radicis -
The weevil's feeding produces
two symptoms - "flagging" of twigs (outer twigs turn reddish brown) from adult
weevil feedings in the spring and death of the tree from larval feeding (girdling) below
the root collar which can occur throughout the year. Adult weevils chew holes in the bark
down to the wood which become covered with white resin and make the twig appear rough
textured. They chew individual holes alone the length of the twig which eventually girdle
it. Larvae feed under the bark on the stem and larger roots below the soil line. Removal
of the soil reveals a black resin soaked appearance to the bark surface and soil around
the root collar. After several years of feeding trees eventually die. The weevil can be
managed by using stump treatments of Lindane or Dursban after each harvest. In heavily
infested plantations, root collars of live trees can be treated with the above
insecticides and Orthene can be applied in August or September to the tree top to kill
newly emerging adult weevils. Also, growers should change to shorter rotations in heavily
infested fields in an effort to salvage as many trees as possible.
WHITE PINE ROOT DECLINE - Verticicladiella procera - Also called Procera Root Rot because the disease attacks other pines besides white pine. The symptoms of this disease can be seen throughout the year. A white pine 5 to 25 feet tall with dull green to yellowish green needles, a thin appearance to the tree crown, and a lack of shoot elongation are symptoms indicating the tree may have this disease. Eventually, the tree will die and turn red in color. Mortality will occur randomly in a plantation or in a windbreak. Occasionally you will observe the disease moving from one tree to the next. Once a tree shows symptoms, the root system is over 75% killed by the fungus. Generally, trees above 25 feet tall do not develop the disease and die. Management for the disease is to remove the white pine including the root system if possible and destroying it. If trees need to be replaced especially in a windbreak, do not plant a pine. Use arborvitae or spruce. This disease continues to be the most common disease reported during the decade.
DIPLODIA TIP BLIGHT - Spaeropsis sapinea - Diplodia
is a serious disease of Austrian and red pine ornamental
trees.
It is also a problem for scotch pine Christmas trees. Infection occurs in the spring
through rain splash disseminated spores entering the new growth of pine. Once the new
shoots begin to harden infection stops. The cool rainy spring will increase infection this
year. Infected shoots turn brown, needles will be stunted, and the shoot may form a
"shepherd's crook", especially on scotch pine. The fruiting bodies are black
spots formed at the needle base under the sheath. They also form on dead twigs and cones.
The disease can be managed by pruning infected shoots during the dry periods of the
summer. Fungicide treatment will prevent infection but must be applied at bud swell and
through shoot elongation for a total of three applications. Benlate and Cleary 3336 are
fungicides that can be used.
POWDERY MILDEW - Microsphaera sp. - Dogwood above 3 feet in height will develop the disease. Foliage that is above 16 feet generally does not show symptoms. Infected trees will have brown or black wilted leaves hanging from the twig. The overall symptoms on the tree makes appear as though drought has caused the tree to drop it's leaves. Only smaller trees twig dieback and mortality have been observed. There is no control for the disease.
TOP DIEBACK of BLACK WALNUT - Seedling to sapling size trees are affected by this disease. In some situations larger trees have been affected. Trees infected dieback to the root collar and sprout from the root collar. Dieback is sudden and usually produces a black wet looking stem. In some trees, a mold and foam may appear at the base of the dieback. The cause of the dieback is unknown, but believed to be caused by bacteria. Ambrosia beetles will attack the trees after dieback has occurred. There is no control for this disease.