By Gail Ruhl, Sr. Plant Disease Diagnostician, P&PDL, Purdue University
Orange rust is now appearing on blackberries and black raspberries in
Indiana; it does not affect red raspberries. The orange rust fungus grows “systemically” throughout
the roots, crown, and shoots of an infected plant, and is perennial inside
the below-ground plant parts. Once a plant is infected by orange rust,
it is infected for life and will produce spores every year after it is
infected. The disease does not normally kill plants, but causes them to
be so stunted and weakened that they produce little or no fruit.
It is important to identify orange rust at the appearance of abnormal
growth of new canes in the spring because infected plants can be easily
identified and removed at this time. Within a few weeks, the lower surface
of infected leaves will be covered with blister-like pustules that are
waxy at first, but soon turn powdery and bright orange. This bright orange,
rusty appearance is what gives the disease its name. Rusted leaves wither
and drop in late spring or early summer. Later in the season, the tips
of infected young canes appear to have outgrown the fungus and may appear
normal. At this point, infected plants are often difficult to identify.
In reality, the plants are systemically infected, and in the following
years infected canes will be bushy and spindly, and bear little or no
fruit.
When diseased plants first appear in early spring, dig them out (including
roots) and destroy them before pustules form, break open, and discharge
the orange masses of spores. If plants are not removed, these spores will
spread the disease to healthy plants. The removal must be complete - new
infected plants will grow from small pieces of roots left in the ground.
Orange rust is also widespread on wild blackberries and black raspberries
in Indiana, thus it is important to not only remove infected plants from
the blackberry planting but to also remove similar plants from wild areas
nearby.
Fungicides with proven effectiveness against this disease have not
been found therefore timely eradication of diseased plants is essential.
For more information, please see the following website: http://ohioline.osu.edu/hyg-fact/3000/3010.html
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Orange Rust of Brambles
Rust |
Orange Rust of Brambles |
By Gail Ruhl, Sr. Plant Disease Diagnostician, P&PDL, Purdue University
Are there more sycamore leaves on your lawn than on your
tree? Do not panic. Your sycamore tree is not dying, it is merely infected
by the most common fungal disease on sycamores in Indiana. This fungal
disease is favored by cool, wet, spring weather.
Symptoms: The most characteristic symptom appears as large irregular
tan to brown necrotic areas that develop along leaf veins, sometimes
expanding to the leaf
margin, causing distortion of the leaf. Twig dieback, wilting and browning
of newly emerging leaves frequently occur. Numerous cankers (localized,
injured
areas) occur on twigs and branches. Severely infected rees may lose
many leaves, beginning at the bottom of the tree, and may appear more
dead than alive.
Disease Cycle: The fungus, Apiognomonia veneta (anamorph: Discula platani),
overwinters in infected leaves and branch and twig cankers. In spring,
spores
are produced and are spread by wind and splashing rain to newly emerging
leaves, buds, shoots, and twigs when conditions are favorable. Spores
are produced from
newly infected tissue, allowing secondary infections to occur.
Management: Even during years of severe infection, sycamore
anthracnose does not result in tree death. The most practical control
is to fertilize
defoliated trees to lessen the stress that comes from having to produce
a second flush of leaves. Spraying is generally not warranted on
large, or older established trees.
For more information, refer to BP-9, Anthracnose of Shade Trees located
on the web at: http://www.agcom.purdue.edu/AgCom/Pubs/BP/BP_9_W.pdf (PDF 496K - Requires Adobe Acrobat to view and print).
You may also download http://www.hort.purdue.edu/ext/HO-140.pdf for
fertilization recommendations.
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Foliar symptoms |
Stem canker and foliar symptoms |
The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by the Purdue University Cooperative Extension Service is implied. Any person using products listed assumes full responsibility for their use in accordance with current direction of the manufacturer. Purdue University is an equal opportunity/equal access institution.
Information listed is valid only for the state of Indiana.
