Controlling Pine Tree Diseases – Symptoms Of Pine Gall Rust Disease

Controlling Pine Tree Diseases – Symptoms Of Pine Gall Rust Disease

By: Mary H. Dyer, Credentialed Garden Writer

Both western and eastern pine gall rust are caused by fungi. You can learn more about these destructive pine trees diseases in this article.

Rust Pine Tree Diseases

There are essentially two types of pine gall rust diseases: western pine gall and eastern pine gall.

Western Pine Gall Rust (Pine-Pine)

Also known as western pine gall rust or as pine-pine gall rust for its proclivity to spread from pine to pine, pine gall rust disease is a fungal disease that affects two- and three-needle pine trees. The disease, caused by a rust fungus known as Endocronartium harknesii, affects Scots pine, jack pine and others. Although the disease is found across much of the country, it is especially widespread in the Pacific Northwest, where it has infected nearly all lodgepole pines.

Eastern Pine Gall Rust (Pine-Oak)

Eastern pine gall rust, also known as pine-oak gall rust, is a similar disease caused by Cronartium quercuum rust. It affects a large number of oak and pine trees.

Although there are some differences between the two diseases, both types of gall rust are easily recognized by round or pear-shaped galls on branches or stems. Although the galls are initially less than an inch (2.5 cm.) across, they grow year by year and can eventually reach several inches (8.5 cm.) in diameter. In time, they may become large enough to girdle stems. However, they often they aren’t noticeable until about the third year.

In spring, the surfaces of mature branches are typically coated with masses of orange-yellow spores, which can infect nearby plants when they are dispersed in the wind. Western pine gall rust requires only one host, as spores from one pine tree can directly infect another pine tree. However, eastern pine gall rust requires both an oak tree and a pine tree.

Pine Gall Rust Treatment

Maintain proper care of trees, including irrigation as needed, as healthy trees are more disease resistant. Although some professionals advise regular fertilization, evidence indicates that the fungus is more likely to affect fast-growing trees, which suggests that use of fertilizer may be counter-productive.

Western pine gall rust generally doesn’t present a serious danger to trees, unless the galls are large or numerous. Fungicides may help prevent the disease when applied at bud break, before spores are released. Control measures are generally not recommended on oak trees.

The best way to control pine gall rust disease is to prune affected areas and remove galls in late winter or early spring, before they have time to produce spores. Remove the galls before they grow too large; otherwise, extensive pruning to remove the growths will affect the shape and appearance of the tree.

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Symptoms on host plants in Pinaceae

Yellow-to-orange spots or bands appear on green needles in spring. Needles turn partly or completely yellow.

In late spring to early summer, tiny, raised, white tubes form on needles breaking open to release powdery, orange spores.

Infected needles may remain attached for several years.

Severe infection causes needles to die, turn brown and fall off.

Lower branches of young trees are most severely affected.

Symptoms on host plants in Asteraceae

Infected leaves develop yellow leaf spots on the upper leaf surface and raised orange spore-filled pustules on the lower leaf surface.

Powdery, yellow-orange spores are produced on the lower leaf surface all summer long.

Dark brown spores appear within leaf spots on the lower leaf surface in late summer and fall.

Plants affected by Pine needle rust in Minnesota


Austrian pine (Pinus nigra)

Ponderosa pine (P. ponderosa)


Daisy fleabane (Erigeron spp.)

Goldenaster (Heterotheca spp.)

Scientific Classification

As listed by the Missouri Botanical Garden and Royal Botanic Gardens at Kew, the genus Pinus consists of 126 species and 35 unresolved species. These trees are subdivided into two subgenera distinguished by their leaf, cone, and seed characteristics.

Subgenus Pinus

Some of the common pine species included in this subgenus are given below:

  • Sikang pine
  • Korean red pine
  • Huangshan pine
  • Khasi pine
  • Masson’s pine
  • Mountain pine
  • Sumatran pine
  • Luchu pine
  • European black pine
  • Red pine
  • Japanese black pine
  • Taiwan red pine
  • Chinese red pine
  • Tropical pine
  • Aleppo pine
  • Turkish pine
  • Canary Island pine
  • Bosnian pine
  • Chir pine
  • Stone pine
  • Ponderosa pine
  • Gray pine
  • Torrey pine
  • Jeffrey pine
  • Apache pine
  • Arizona pine
  • Coulter pine
  • Lodgepole pine
  • Sand pine
  • Virginia pine
  • Loblolly pine
  • Cuban pine
  • Spruce pine
  • Caribbean pine
  • Shortleaf pine
  • Longleaf pine
  • Chihuahua pine
  • Jack pine

Subgenus Strobus

Some of the white and soft pines included in this subgenus are listed here.

  • Foxtail pine
  • Colorado pinyon
  • Mexican pinyon
  • Border pinyon
  • Weeping pinyon
  • Parry pinyon
  • Potosi pinyon
  • Texas pinyon
  • Nelson’s pinyon
  • Eastern white pine
  • Siberian pine
  • Blue pine
  • Mexican white pine
  • Swiss pine
  • Limber pine
  • Chinese white pine
  • Bhutan white pine

Aside from the different pine species that are mentioned above, several cultivars including ‘Dragon’s Eye’ Korean pine, ‘Oregon Green’ Austrian pine, ‘Watereri’ Scots pine, ‘Nisbet’s Gold’ Scots pine, ‘Joppi’ Jeffrey pine, ‘Cleary’ Japanese white pine, and ‘Winter Sun’ mountain pine have been produced.

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  • 1 Impacts
  • 2 Life cycle
  • 3 Host plant-rust fungus relationship
  • 4 Infection process
  • 5 Common rust fungi in agriculture
  • 6 Management of rust fungi diseases
    • 6.1 Home control
    • 6.2 Commercial control
    • 6.3 Host plants affected
  • 7 Hyperparasites of rusts
  • 8 Gallery
  • 9 See also
  • 10 References
  • 11 External links

Rusts are considered among the most harmful pathogens to agriculture, horticulture and forestry. Rust fungi are major concerns and limiting factors for successful cultivation of agricultural and forest crops. White pine blister rust, wheat stem rust, soybean rust, and coffee rust are examples of notoriously damaging threats to economically important crops. [1]

All rusts are obligate parasites, meaning that they require a living host to complete their life cycle. They generally do not kill the host plant but can severely reduce growth and yield. [4] Cereal crops can be devastated in one season oak trees infected in the main stem within their first five years by the rust Cronartium quercuum often die. [5]

Rust fungi can produce up to five spore types from corresponding fruiting body types during their life cycle, depending on the species. Roman numerals have traditionally been used to refer to these morphological types.

  • 0-Pycniospores (Spermatia) from Pycnidia. These serve mainly as haploidgametes in heterothallic rusts.
  • I-Aeciospores from Aecia. These serve mainly as non-repeating, dikaryotic, asexual spores, and go on to infect the primary host.
  • II-Urediniospores from Uredia (Uredinia). These serve as repeating dikaryotic vegetative spores. These spores are referred to as the repeating stage because they can cause auto-infection on the primary host, re-infecting the same host on which the spores were produced. They are often profuse, red/orange, and a prominent sign of rust disease.
  • III-Teliospores from Telia. These dikaryotic spores are often the survival/overwintering stage of the life cycle. They usually do not infect a plant directly instead they germinate to produce basidia and basidiospores.
  • IV-Basidiospores from Teliospores. These windborne haploid spores often infect the alternate host in Spring. [6][7] They are rarely observed outside of the laboratory.

Rust fungi are often categorized by their life cycle. Three basic types of life cycles are recognized based on the number of spore types as macrocyclic, demicyclic, and microcyclic. [1] The macrocyclic life cycle has all spore states, the demicyclic lacks the uredinial state, and the microcyclic cycle lacks the basidial, pycnial, and the aecial states, thus possess only uredinia and telia. Spermagonia may be absent from each type but especially the microcyclic life cycle. In macrocyclic and demicyclic life cycles, the rust may be either host alternating (heteroecious) (i.e., the aecial state is on one kind of plant but the telial state on a different and unrelated plant), or non-host alternating (autoecious) (i.e., the aecial and telial states on the same plant host). [1] Heteroecious rust fungi require two unrelated hosts to complete their life cycle, with the primary host being infected by aeciospores and the alternate host being infected by basidiospores. This can be contrasted with an autoecious fungus which can complete all parts of its life cycle on a single host species. [6] Understanding the life cycles of rust fungi allows for proper disease management. [8]

There are definite patterns of relationship with host plant groups and the rust fungi that parasitize them. Some genera of rust fungi, especially Puccinia and Uromyces, comprise species that are capable of parasitizing plants of many families. Other rust genera appear to be restricted to certain plant groups. Host restriction may, in heteroecious species, apply to both phases of life cycle or to only one phase. [1] As with many pathogen/host pairs, rusts are often in gene-for-gene relationships with their plants. This rust-plant gene-for-gene interaction differs somewhat from other gene-for-gene situations and has its own quirks and agronomic significance.

The spores of rust fungi may be dispersed by wind, water or insect vectors. [9] When a spore encounters a susceptible plant, it can germinate and infect plant tissues. A rust spores typically germinates on a plant surface, growing a short hypha called a germ tube. This germ tube may locate a stoma by a touch responsive process known as thigmotropism. This involves orienting to ridges created by epidermal cells on the leaf surface, and growing directionally until it encounters a stoma. [10]

Over the stoma, a hyphal tip produces an infection structure called an appressorium. From the underside of an appressorium, a slender hypha grows downward to infect plant cells [11] It is thought that the whole process is mediated by stretch-sensitive calcium ion channels located in the tip of the hypha, which produce electric currents and alter gene expression, inducing appressorium formation. [12]

Once the fungus has invaded the plant, it grows into plant mesophyll cells, producing specialized hyphae known as haustoria. The haustoria penetrate cell walls but not cell membrances: plant cell membranes invaginate around the main haustorial body forming a space known as the extra-haustorial matrix. An iron and phosphorus rich neck band bridges the plant and fungal membranes in the space between the cells for water flow, known as the apoplast, thus preventing the nutrients reaching the plant's cells. The haustorium contains amino acid and hexose sugar transporters and H + -ATPases which are used for active transport of nutrients from the plant, nourishing the fungus. [13] The fungus continues growing, penetrating more and more plant cells, until spore growth occurs. The process repeats every 10 – 14 days, producing numerous spores that can be spread to other parts of the same plant, or to new hosts.

  • Cronartium ribicola(White pine blister rust) the primary hosts are currants, and white pines the secondary. Heterocyclic and macrocyclic
  • Gymnosporangium juniperi-virginianae(Cedar-apple rust) Juniperus virginiana is the primary (telial) host and apple, pear or hawthorn is the secondary (aecial) host. Heteroecious and demicyclic
  • Hemileia vastatrix(Coffee rust) Primary host is coffee plant unknown alternate host. Heteroecious
  • Phakopsora meibomiae and P. pachyrhizi(Soybean rust) Primary host is soybean and various legumes. Unknown alternate host. Heteroecious
  • Puccinia coronata(Crown Rust of Oats and Ryegrass) Oats are the primary host Rhamnus spp. (Buckthorn) is alternate host. Heteroecious and macrocyclic
  • Puccinia graminis (Stem rust of wheat and Kentucky bluegrass, or black rust of cereals) Primary hosts include: Kentucky bluegrass, barley, and wheat Common barberry is the alternate host. Heteroecious and macrocyclic
  • Puccinia hemerocallidis(Daylily rust) Daylily is primary host Patrina sp is alternate host. Heteroecious and macrocyclic
  • Puccinia triticina(Brown Wheat Rust) in grains
  • Puccinia sorghi(Common Rust of Corn)[15]
  • Puccinia striiformis(Yellow Rust) of cereals
  • Uromyces appendiculatus(Bean Rust) in common bean (Phaseolus vulgaris) [16]
  • Puccinia melanocephala(Brown Rust of Sugarcane)
  • Puccinia kuehnii(Orange rust of Sugarcane)

The control methods of rust fungus diseases depend largely on the life cycle of the particular pathogen. The following are examples of disease management plans used to control macrocyclic and demicyclic diseases:

Macrocyclic Disease: Developing a management plan for this type of disease depends largely on whether the repeating stage (urediniospores) occur on the economically important host plant or the alternate host. For example, the repeating stage in white pine blister rust disease does not occur on white pines but on the alternate host, Ribes spp. During August and September Ribes spp. give rise to teliospores which infect white pines. Removal of the alternate host disrupts the life cycle of the rust fungi Cronartium ribicola, preventing the formation of basidiospores which infect the primary host. Although spores from white pines cannot infect other white pines, survival spores may overwinter on infected pines and reinfect Ribes spp. the following season. Infected tissue is removed from white pines and strict quarantines of Ribes spp. are maintained in high risk areas. [6] [17]

Puccinia graminis is a macrocyclic heteroecious fungus that causes wheat stem rust disease. The repeating stage in this fungus occurs on wheat and not the alternate host, barberry. The repeating stage allows the disease to persist in wheat even though the alternate host may be removed. Planting resistant crops is the ideal form of disease prevention, however, mutations can give rise to new strains of fungi that can overcome plant resistance. Although the disease cannot be stopped by removal of the alternate host, the life cycle is disrupted and the rate of mutation is decreased because of reduced genetic recombination. This allows resistance bred crops to remain effective for a longer period of time. [6] [18]

Demicyclic Disease: Because there is no repeating stage in the life cycle of demicyclic fungi, removal of the primary or the alternate host will disrupt the disease cycle. This method, however, is not highly effective in managing all demicyclic diseases. Cedar-apple rust disease, for example, can persist despite removal of one of the hosts since spores can be disseminated from long distances. The severity of Cedar-apple rust disease can be managed by removal of basidiospore producing galls from junipers or the application of protective fungicides to junipers. [19]

Home control Edit

Rust diseases are very hard to treat. Fungicides such as Mancozeb or Triforine may help but may never eradicate the disease. Some organic preventative solutions are available and sulphur powder is known to stop spore germination. High standards of hygiene, good soil drainage, and careful watering may minimize problems. Any appearance of rust must be immediately dealt with by removing and burning all affected leaves. Composting, or leaving infected vegetation on the ground will spread the disease.

Commercial control Edit

In some large acreage crops, fungicides are applied by air. The process is expensive and fungicide application is best reserved for seasons when foliar diseases are severe. Research indicates, the higher the foliar disease severity, the greater the return from the use of fungicides. [20] Southern corn rust disease, can be confused with common rust. Southern rust's distinguishing characteristic is that pustules form mostly on the upper leaf surface and spores are more orange in color. Southern rust spreads more quickly and has a higher economic impact when hot, humid weather conditions persist. Timely fungicide applications to control southern rust are more crucial than with common rust. [21]

A variety of preventative methods can be employed for rust diseases:

  • High moisture levels may exacerbate rust disease symptoms. The avoidance of overhead watering at night, using drip irrigation, reducing crop density, and using fans to circulate air flow may decrease disease severity.
  • The use of rust resistant plant varieties
  • Crop rotation can break the disease cycle because many rusts are host specific and do not persist long without their host.
  • Inspection of imported plants and cuttings for symptoms. It is important to continuously observe the plants because rust diseases have a latent period (plant has the disease but shows no symptoms).
  • Use of disease-free seed can reduce incidence for some rusts [18]

Host plants affected Edit

It is probable that most plant species are affected by some species of rust. Rusts are often named after a host species that they infect. For example Puccinia xanthii infects the flowering plant cocklebur (Xanthium). Recently, a total of 95 rust fungi belonging to 25 genera associated with 117 forest plant species belonging to 80 host genera under 43 host families were reported from the Western Ghats, Kerala, India. [1] Rust fungi include:

  • Aecidium
  • Cerotelium
  • Chaconia
  • Coleosporium
  • Crossopsora
  • Didymopsorella
  • Hamspora
  • Hapalophragmidium
  • Hemileia
  • Kernkampella
  • Kuehneola
  • Kweilingia
  • Macabuna
  • Maravalia
  • Melampsora
  • Olivea
  • Physopella
  • Puccinia
  • Ravenelia
  • Uraecium
  • Uredo
  • Uredopeltis
  • Uromyces
  • Xenostele
  • Zaghouania

Rust infected host genera include: [1]

  • Acacia
  • Acalypha
  • Ageratina
  • Albizia
  • Arundinaria
  • Bambusa
  • Bidens
  • Blepharis
  • Bombax
  • Bridelia
  • Callicarpa
  • Canarium
  • Canthium
  • Catunaragam
  • Cinnamomum
  • Cissus
  • Cleistanthus
  • Clerodendron
  • Coffea
  • Coix
  • Cosmostigma
  • Crotalaria
  • Dalbergia
  • Dendrocalamus
  • Derris
  • Diospyros
  • Dipterocanthus
  • Elaeagnus
  • Elephantopus
  • Elettaria
  • Eragrostis
  • Euphorbia
  • Ficus
  • Flacourtia
  • Grewia
  • Holarrhena
  • Holoptelia
  • Hypericum
  • Ichnocarpus
  • Ischaemum
  • Jasminum
  • Justicia
  • Loesneriella
  • Luvunga
  • Meiogyne
  • Meliosma
  • Mimusops
  • Morus
  • Neolitzea
  • Ocimum
  • Olea
  • Oxalis
  • Pavetta
  • Persicaria
  • Phyllanthus
  • Plectranthus
  • Plumeria
  • Pongamia
  • Premna
  • Protasparagus
  • Rubus
  • Salix
  • Spondia
  • Strobilanthes
  • Strychnos
  • Tabernaemontana
  • Terminalia
  • Toddalia
  • Trichosanthes
  • Vernonia
  • Vigna
  • Wrightia
  • Xanthophyllum
  • Xylia
  • Ziziphus

Some of the better known hosts include:

  • Arisaema triphyllum, Jack-in-the-pulpit
  • Avena sativa, Oats
  • Berberis vulgaris, Common barberry
  • Vicia faba - Broad beans
  • Coffea arabica - Coffee
  • Crataegus monogyna - Hawthorn
  • Chrysanthemum
  • Cydonia - Quince
  • Euphorbia maculata, Spotted Spurge
  • Fuchsia spp,
  • Garlic
  • Hordeum vulgare, Barley
  • Juniperus virginiana, Red Cedar (Juniper apple disease)
  • Juniperus communis - Juniper
  • Allium ampeloprasum - Leek
  • Malus – Apple
  • Mentha piperita - Peppermint
  • Mespilus - Medlar
  • Onion
  • Pelargonium
  • Primula veris
  • Primula vulgaris
  • Pyrus - Pear
  • Rosa spp, Roses
  • Triticum spp., Wheat
  • Oxalis spp., Oxalis
  • Secale cereale, Rye
  • Senecio vulgaris -Common groundsel
  • Xanthium canadense Cocklebur

In the family Sphaeropsidaceae of Sphaeropsidales fungi, species of the genus Darluca are hyperparasites on rusts. [22]

American Chestnut Blight

Attacks hardwoods - Chestnut blight is a fungus that has virtually wiped out the American chestnut, as a commercial species, from eastern hardwood forests. Although roots from trees cut or killed many years ago continue to produce sprouts that survive to the sapling stage before being killed, there is no indication that a cure for this disease will be found. The fungus is widespread and continues to survive as a non-lethal parasite on chinkapin, Spanish chestnut, and post oak.

Common Pests and Diseases

When a Scots pine develops yellowing needles along a single branch, this may be a sign of a pine wilt disease, called Cyclaneusma needle cast. Consult an expert for confirmation, and remove the entire tree if it is infected, as this fungal disease is incurable.

Western gall rust and Lophodermium needle cast are also common in some areas.

A number of pests are known to affect Scots pine including:

  • Pine spittlebug (Aphrophora parallela)
  • European pine sawfly (Neodiprion sertifer)
  • Pine root collar weevil (Hylobius radicis)
  • Giant conifer aphid (Cinara spp.)
  • Pine needle scale (Chionaspis pinifoliae)
  • White pine weevil (Pissodes strobi)
  • Pine root tip weevil (Hylobius rhizophagus)
  • Zimmerman pine moth (Dioryctria zimmermani)

Porcupines and birds, especially pine grosbeak, may also cause damage to the tree.

Watch the video: Pine Tree Problems