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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Evergreen Trees and Shrubs > Pine > Slow growth, discolored needles

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Pine > Needles > Slow growth, discolored needles, thin canopy throughout the entire tree

1 of 6
  • Ips bark beetles 1
  • Ips bark beetles 2
  • Ips bark beetles 3

Ips bark beetles
Ips spp..

  • Adults bore numerous holes less than 1/8 inch diameter in bark which can resemble being shot by a BB gun or shot gun
  • Entrance holes often have a reddish-brown, resin-soaked fine sawdust
  • Larvae feed under bark
  • Needles turn yellow and reddish-brown
  • Adults are dark brown to black and range in size from about 1/8 to ¼ of an inch long
  • Favors stressed pines of all species
  • More information on Ips bark beetles...
2 of 6
  • Armillaria root rot 1
  • Armillaria root rot 2
  • Armillaria root rot 3

Armillaria root rot
Armillaria spp.

  • Infected trees have reduced growth, discolored needles, thin canopies; produce large amount of cones and eventually die
  • Flat white sheets of fungal growth (mycelial fans) between the bark and sapwood at the base of infected trees
  • Base of tree may be encrusted in resin
  • Thick, black shoestring-like fungus can sometimes be seen under the bark at the root collar and in the soil near the base of the tree
  • Wood is decayed, white, soft and spongy, beginning with the roots and may extend from the base of the tree well up into the trunk
  • Trees frequently break or fall over in storms
  • Clusters of honey-colored mushrooms may grow at the base of the tree in fall
  • More information on Armillaria root rot...
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  • Tomentosus root rot 1
  • Tomentosus root rot 2
  • Tomentosus root rot 3

Tomentosus root rot
Onnia tomentosa

  • Infected trees have reduced growth, discolored needles, thin canopies; produce large amount of cones and eventually die
  • Heartwood of infected roots and trunks decays, initially turning reddish-brown
  • As infection continues white pocket rot develops; decayed wood has elongated pockets or pits and may appear honeycomb-like in cross section
  • Affected trees are often scattered, not adjacent
  • Infected trees frequently break or lodge during storms
  • Large mushrooms, velvety brown above and porous, buff-colored below occur at base of tree or above decaying roots some distance away
  • More information on Tomentosus root rot...
4 of 6
  • Brown root and butt rot 1
  • Brown root and butt rot 2
  • Brown root and butt rot 3

Brown root and butt rot
Phaeolus schweinitzii

  • Slow growth, thin canopy and discolored needles in severely infected trees
  • Infection causes decay of heartwood in trunk and roots
  • Decaying wood has brown, cubical rot
  • Affected trees are often scattered, not adjacent
  • Infected trees frequently break or lodge in storms
  • 10"-12" fungal conk growing on trunk or several feet away from tree, velvety dark brown above and porous, light brown underneath
  • Most pines and conifers are susceptible
  • More information on Brown root and butt rot...
5 of 6
  • Pine root collar weevil 1
  • Pine root collar weevil 2
  • Pine root collar weevil 3

Pine root collar weevil
Hylobius radicis

  • Large amounts of pitch are exuded, darkening the root collar and nearby soil
  • Discolored needles, from yellow to reddish-brown on entire tree
  • Infested trees often tip due to feeding damage
  • Most pine attacked; prefers pine growing on sandy soils with heavy grass competition
  • Adults are ¼ inch long, reddish brown to black with whitish to yellowish spots (patches of scale); has conspicuous snout
  • Larvae about ⅓ inch long, whitish and grub-like
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  • Heterobasidion root disease and butt rot 1
  • Heterobasidion root disease and butt rot 2
  • Heterobasidion root disease and butt rot 3

Heterobasidion root disease and butt rot
Heterobasidion irregulare (previously known as H. annosum)

  • Slow growth, thin canopy, and discolored needles in severely infected trees
  • Resin soaked bark at base of tree
  • Sapwood of roots and butt discolored brown
  • Groups of infected trees commonly found in area where trees have been removed
  • Wood decays with a stringy white rot
  • Trees eventually die, windthrow common
  • Popcorn like white fungal structures that grow into leathery fungal conk, white to reddish brown above, cream colored with multiple pores below
  • Fungal conks common on cut stumps but often rare on infected trees
  • Infects most pines and other conifers
  • Not yet identified in Minnesota; if found, call Minnesota Dept. of Agriculture at 651-201-6684 or 1-888-545-6684
  • More information on Heterobasidion root disease and butt rot...

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