What Are the Yellow Balls on the Jack Pine?

Peridermium harknessii

Pine-Pine Galls sporing on Jack Pine

Last summer I was asked by a friend what the yellow balls infesting his Jack Pines (Pinus banksiana) were. They were obviously some kind of gall forming rust and were quite striking even from a distance.

Peridermium harknessii

Pine-Pine Galls sporing, note spores on needles and bark below left hand gall.

The rust was Peridermium harknessii and it goes by a variety of common names such as Western Gall Rust, Pine-Pine Gall Rust, and Rust Pine Yellow Disease. It has been placed by some taxonomists into the genus Endocronartium.

Peridermium harknessii

Pine-Pine Galls are inconspicuous when not sporing.

Peridermium harknessii

The bright yellow spores are unmistakable.

It is common in the Jack Pine Plains near Grayling. The yellow spores appear in late May or June from the semi-spherical galls. A gall will produce spores for several years. The woody gall remains on the branch or trunk throughout the year and will persist after the branch dies. It is not a serious pest in Michigan and the hosts are killed only if the rust infects the main trunk of small trees. Infected mature trees often only lose a few branches.

Peridermium harknessii

The remains of a Pine-Pine Gall persist long after the branch dies.

Unlike many rusts, Pine-Pine Gall Rust has a single host cycle. Meaning that it spores and directly infects other pines. I have only seen this species, in Michigan, on Jack Pine but it has been reported on Scots Pine (Pinus sylvestris). My blog post regarding Poison Ivy Rust presents further details on the life cycles of various rusts.

Look for this colorful species in late spring.
Copyright 2017 by Donald Drife

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What is Killing the Jack Pine?

Sphaeropsis shoot blight

Sphaeropsis shoot blight

Last Fall, my friend Trapper Dave contacted me and asked what was killing the Jack Pine (Pinus banksiana) in a Kirtland’s Warbler planting near his cabin in Oscoda County. This planting was the subject of an earlier blog post. Needles on branches and entire trees suddenly turned brown. We checked other plantings and found dead trees several other places in Oscoda, Crawford, and Montmorency counties. Several of these stands were two year old Kirtland’s Warbler plantings and we became concerned about the impact this die-off might have on this endangered bird.

Trapper Dave contacted the DNR and a helpful Forest Health Technician replied that, “We have had several reports from roughly a four county area of this type of mortality. The pictures you sent are consistent with other pictures we have received from this area… I’ll be sure to send you a some more information once we are able to make a diagnosis.”

Later we received a report from the Diagnostic Services at Michigan State University. They identified Sphaeropsis canker (Sphaeropsis sp. or spp) as the cause of the die-off. From the limited sample, submitted by the Forest Technician, they could not identify which species it was or even if more than one species is involved. The genus is poorly understood and probably has many undescribed species.

Sphaeropsis shoot blight

Jack Pine needles showing Sphaeropsis shoot blight

I looked up the fungus in Tree Maintenance (6th edition) by Pirone, Hartman, Sall, and Pirone. They list another newer generic name, Diplodia but use Sphaeropsis. They write that the fungus “overwinters in infected needles, twigs, and cones. In spring, the small fruiting bodies release egg-shaped, light brown spores… The fungus grows down through the needles and into the twigs, where it destroys tissues as far back as the first node.” (page 425).

Sphaeropsis shoot blight

Close-up of needle showing Sphaeropsis shoot blight spores

Several sources state that the spores overwinter in the cones but I could not find spores in the half-dozen cones I checked. The fungus kills the branches quickly. Die-off appeared over a two-week period but the trees must have been infected for most of the summer.

A USDA Northeastern Area Fact Sheet states, “Sphaeropsis shoot blight, formerly called Diplodia shoot blight, is worldwide in distribution and can infect many conifer hosts. Although many pine species are reported hosts, this disease causes severe damage only to trees that are predisposed by unfavorable environmental conditions. …Other predisposing environmental factors include poor site, drought, hail or snow damage, compacted soils, excessive shading, insect activity or other mechanical wounding. In the north-central United States, the most common hosts are Austrian, Scotch, mugo, red and jack pines grown in ornamental and windbreak plantings.”

We need to monitor the extent of the shoot blight damage in the Grayling area. It is a native fungus attacking a native tree that should have defense mechanisms. It was a dry year in the Grayling area so this may have made the trees more susceptible to infection. I am concerned that the USDA lists Jack Pine plantings, which of course is what we do for Kirtland’s Warbler, as being more susceptible to the infection. I did not find the fungus in the half dozen naturally occurring Jack Pine stands that I checked. If you find this fungus please report the location in the comments section of this blog post.
Copyright 2016 by Donald Drife

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Jack Pine Management

Setophaga kirtlandii

Male Kirtland’s Warbler

In the northern half of Michigan’s Lower Peninsula 150000 acres, approximately 235 square miles, of mainly Jack Pine (Pinus banksiana) are managed to provide habitat for the endangered Kirtland’s Warbler (Setophaga kirtlandii). At any given time approximately 38,000 acres are suitable nesting habitat.

After an area is logged, it is furrowed and then planted with 6 inch [15 cm] tall Jack Pine seedlings. Some Oaks (Quercus spp.) and some tall Pines (Pinus spp.) are left to provide perching sites for the warbler’s territorial singing. Jack Pines are not planted in continuous stands but contain grassy openings. Kirtland’s Warblers nest on the ground, normally at the edges of these openings. When the pines are 5-8 feet (2-3m) in height nesting begins. Nesting continues as long as there are branches touching the ground and the branches of adjoining trees. Four to eight years are required for the pines to reach nesting size and they are suitable for nesting for 12-15 years. After another 30 years or so, the forest is cut for pulpwood and the cycle begins again.

Photo by Bob Anderson copyright 2009

Figure 1 Photo by Bob Anderson copyright 2009

Figure no. 1 shows a Kirtland planting at the end of its first year. Furrows are still visible and you can see the tops of seedling Jack Pines. Figure no. 2 shows the same area five years later. Oak #1 has grown but the “pine stand” is mostly unchanged. Kirtland’s Warblers started to nest in the Figure no. 2 stand.

Photo by Dave Bissonette copyright 2014

Figure 2 Photo by Dave Bissonette copyright 2014

Management areas produce habitat for other species. Hill’s Thistle (Cirsium hillii) is a state threatened species. At most two feet [.6m] high it has large, pink, flowers that dot the plantings. Wood Lily (Lilium philadelphicum) and Sweet-Fern (Comptonia peregrina) also inhabit the areas.  Northern Apple Sphinx Moth larva (Sphinx poecila) feed on Sweet-fern.

Cirsium hillii

Hill’s Thistle

Sphinx poecila

L Northern Apple Sphinx Moth larva R Wood Lily

The Kirtland’s management areas are helping the warbler to recover. It is also altering the landscape, providing homes for a large number of other species.
Copyright 2015 by Donald Drife

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Hello to Mr. Olson’s class at Coweta High School, Coweta, Oklahoma.

Michigan Pines

Pinus strobus banksiana resinosa sylvestris

Pine needles: l-r White, Jack, Red (Black similar), Scots

Michigan has three native species of Pine trees and two widely established non-native species. Two additional species have been recorded in the Michigan Flora database but currently they rarely escape. They are Pitch Pine (Pinus rigida) and Ponderosa Pine (P. ponderosa). Both of these species have needles in groups of three.

Pinus strobus White Pine

White Pine

White Pine (P. strobus) is native and easy to recognize with its needles in groups of five. They are fine, soft needles. Its cones are three times as long as they are wide. This is the state tree of Michigan. This was the preferred pine species during Michigan’s lumber era, because it occurred in pure stands and floated well.

Pinus banksiana cones

Jack Pine: Pollen cones l, Seed cones r

Jack Pine (P. banksiana) is native occurring mostly north of Saginaw but coming south along the Lake Michigan coast to the state line. It has two, 2-4 cm (3/4” to 1 1/2”) long needles in each cluster. They are normally twisted. Its bark is dark red to dark gray and at times looks as if it is covered by burnt corn flakes. Bent cones are another distinguishing character of this tree. It is often stated that fire is required to open the cones but I commonly see open cones hanging on trees.

Pinus banksiana Jack Pine

Jack Pine

It is among young Jack Pines that Kirtland’s Warblers nest. This is a short-lived species; a sixty year old Jack Pine is ancient whereas a sixty year old Red or White Pine is still a teenager. Jack Pine is normally a small tree, reaching 15 m (50 feet) in height. I watched one Jack Pine for a decade that crept along the ground, never reaching more than 1 m (3 feet) in height but becoming 5 m (16 feet) long before it died.

Pinus banksiana l_Pinus sylvestris r

Jack Pine background left, Scots Pine foreground left and right

Pinus sylvestris  Scots Pine

Scots Pine

Scots Pine or Scotch Pine (P. sylvestris) is a Eurasian species that has been planted extensively in Michigan. Mature trees have a distinct reddish-orange bark in the upper tree trunk. The needles are similar to Jack Pines making immature trees difficult to separate. I hit my palm against the end of the needles and if they feel sharp then it is a Scots Pines. The needles are sometimes glaucous (with a waxy bloom) and tend to be slightly longer than Jack Pine needles. Cones on Scots Pines are straight and open in the second year.

Pinus nigra bark l P. resinosa c P. resinosa r

l-r Black Pine bark, Red Pine bark, Red Pine branch and cone

Red Pine (P. resinosa) is a native growing mostly north of Flint. It has two, 10-15 cm (4” to 6”) long needles in each cluster. When bent the needles break. This species has reddish-brown winter buds. Its common name comes from the flaky, reddish upper bark. Stumps, 110 years old, dot the field at our cabin near Grayling. Red Pines normally occur in mixed stands with Oaks (Quercus sp), Cherries (Prunius sp) or White Pine. They were lumbered later than the pure stands of White Pine.

Pinus nigra l P. resinosa r winter bud

Terminal buds l-r Black Pine (with first-year cone), Red Pine

Pinus nigra l P. resinosa r

cones l-r Black Pine (turned upside-down to show prickle), Red Pine

Black Pine or Austrian Pine (P. nigra) is an European species that is widely planted in the Great Lakes Region. The needles are similar to Red Pine but they are flexible. This species has black bark and appears denser having more needle clusters and branches than a Red Pine. Its winter buds are whitish and sticky. Black Pine cones have prickles on their umbos and Red Pines have flattened umbos. An umbo is the shield-like structure on a pine cone’s scale. Black Pine cones are yellowish-green before they open.

Pinus nigra  Black Pine

Black Pine

Copyright 2014 by Donald Drife

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