Philley, George L.

Smith, Leon R.

English

Texas A&amp;M Repository

A\ BLACKBERRY DISEASES AND THEIR CONTROL Daniel C. Pfannstid. Dicector College Station. Texas Blossom infected with rosette fungus shown at right in , droto a b o ~  and ea lcft ia bottonr photo. Cover photo: Orange rust on "Humbk" v-. - ",J- DLACKBERRY DISEASES AND THEIR CONTROL George L. Philley and Leon R. Smith* Blackberries and dewberries often are attacked by a variety of disease-producing organisms. The major- ity of these are fungi, but severarspecies of nematodes and at least one virus may also 'weaken plants and reduce quality and yield of berries. The perennial na- ture of berry plants favors build-up of disease or- ganisms over a period of time, so  that the productive life of plantings often falls far short of expectations. An understanding of these diseases, the organisms that cause them and the conditions required for their de- velopment will help berry growers establish and main- tain healthy, productive plants. --Crown Gall Crown gall disease is caused by tumor-inciting bacteria present either in the soil at planting time or on propagative root cuttings. The disease can be recog- nized by the presence of galls or tumors on the roots or on the crowns either below or just above the soil line. Galls may range from pea-size or smaller up to several inches in diameter. Plants may be stunted or weakened by crown gall bacteria. This makes them susceptible to invasion by other soil organisms. Control of crown gall depends almost entirely on planting gall-free blackberries in clean soil. Avoid planting at old berry sites or where other host plants such as rose or fruit trees have been established pre- viously. *Extension plant pathologist and Extension agent-plant pathol- ogy (pest management), The Texas A&M University System. Crown g 8 Y  diuuc. Nematodes Several nematode species are parasitic to black- berries and dewberries. Soil populations of these parasites may increase considerably a s  plants age, re- sulting in dwarfed fruiting canes and smaller fruit. Damage generally is most severe in light, sandy soils. During hot summer months or under severe moisture stress, foliage of heavily infested plants may turn yellow and drop early. A practical approach to nematode control in com- mercial fields and in home gardens consists of plant- ing clean root cuttings in soil where only grasses or small grains have been allowed to grow for 3 to 4 years. In the absence of suitably clean land, soil may be treated with an approved pre-plant soil fumigant  to^ reduce nematode populations to acceptable levels. 2 .  Anthracnsse, sometimes called dieback, is a common foliage and cane disease of blackberries and is first noticeable in the spring on new shoots and a s  purple- bordered spots an h u e s .  As spots on canes enlarge, shape and gradually turn gray. dry out, crack, and cane tips die ome white with age, and affected out leaving a shot-hole effect. The c a d  fungus also attacks fruit, resulting in small, dry, scabby berries. Certain berry varieties, such as Boysen, Young and Ness, are very susceptible to an- thracnose; Brazos is moderately susceptible; and mect types, such a s  Humble, Lawton and Cherokee, .8re least affected by the disease. Anthracnose control on susceptible varieties is accomplished by a combination of cultural practices chemical control. Before planting, destroy any the immediate area. In humid areas se is likely to cause greatest damage, ant varieties should be used. Plant at sites having good air movement, and space plants wide enough apart to permit good air circulation. For established plants, remove and bum bdl badly infested canes soon after harvest. Weed and grass growth in the row should be kept down for good eir circulation around plants. Chemical control of anthracnose on  susceptible varieties involves three to four fungicide spray appli- cations, beginning in early spring when leaf buds have swelled or are just beginning to open. Timing of the I first application is very important in preventing later buildup of the causal fungus. Use Captang, basic copper sulfate or lime sulfur, making sure all plant parts are covered thoroughly with spray material. Orange Rust Orange rust disease is caused by a fungus that moves systemically throughout infected plants, rendering them useless for future production. In com- , mercial production fields of East Texas, it is most 1 serious on the Humble blackberry. This disease is recognized easily by the large mas- h ses of oran, colored spores produced in the spring L I Anthracnose cane lesions. on the leaves of affected plants. As leaf expansion is completed in late March or early April, large orange pustules form on the undersides of leaves, often caus- ing distortion and upward leaf rolling. The pustules rupture and release spores for a period of about 60 days. Rust symptoms then disappear, but foli; remains sickly in appearance. All new canes produc- on affected plants will be non-productive. Control of orange rust is limited to cultural prac- tices that prevent spread of the disease and the use of resistant varieties. Remove all infested plants, includ- ing complete root systems, as  soon as pustules be- come noticeable in the spring and before spores are released. Fungicidal sprays have not provided satis- factory control. Boysen, Eldorado, Lawt on and Young varieties are resistant to orange rust disease. Brazos is practically immune. Rosette Rosette, also known as  double-blossom or witch's broom, is another fungal disease that prevents normal fruit development. Both wild and cultivated black- berries and dewberries are susceptible. Observations made at the Overton Research and Extension Center indicate varieties differ in their susceptibility to rosette. Humble has high resistance, whereas Comanche and Cheyenne are very susceptible. Cherokee, Bryson and Womack are moderately sus- ceptible. Brazos and Rosborough are moderately re- sistant. Varietal resistance may not be permanent be- cause there have been recent reports of an increase in rosette on the Brazos variety in Southeast Texas. Symptoms of rosette are short, broom-like clus- ters of foliage arising from infected canes. Flower buds on infected canes may appear somewhat larger and redder than normal. At flowering, petals may appear wrinkled or distorted, and sepals of the bract much elongated. Blossoms on infected canes, or blossoms recently infected by aerial spores of the fungus, fail to make fruit. On damp mornings, close examination will reveal a network of light gray fungal growth on af- fected flower parts. Control of rosette requires removing affected canes a s  soon as  they become noticeable. Destroy all wild berry plants in the vicinity. Remove and burn all fruiting canes soon after harvest and keep plants adequately spaced for good air circulation. Where heavy infection has occurred, mowing all canes to the ground may be necessary. Do this soon after har- low production of new canes for the next other than those caused by the an- fall. On rare occa- reserve foliage and disease is caused by a virus. Infected urces of virus infection. Removing infected d roots and destroying wild brambles will re- ead of the virus to healthy plants. Obtain blackberry plants from reputable sources where sterility disease is not a problem. Conclusion Good cultural practices play an important role in blackberry disease control : 1. When possible, select varieties with resistance to diseases common in your area. 2. Examine roots before planting to ensure ab- sence of crown gall. 3. Do not propagate cuttings from diseased plants. 4. Choose planting sites with good air circulation. 5. Destroy all wild berry plants and brambles inl nearby fence rows or in the vicinity of the plant- ing site. 6. After harvest, remove and burn the old fruit canes and any new canes that appear diseased. 7. Thin healthy canes for good air circulation, and prevent excessive weed growth in the rows. Educational programs conducted by the Texas  Agricultural Exten- sion Service serve people of all ages  regardless o j  socioeconomic level, race ,  color, sex,  religion o r  national origin. Cooperative Extension Work in Agriculture and Home Economics, The  Texas  A&M University System and the United States Depart- ment of Agriculture cooperating. Distributed in furtherance of the Acts of Congress  of May 8. 1914, as amended, and June 30. 1914. 10M - 3-82. Revision PP Rr HORT 2- 1 

Blackberry Diseases and Their Control.

Texas A&M University

A\ 
BLACKBERRY DISEASES 
AND THEIR CONTROL 
Daniel C. Pfannstid. Dicector 
College Station. Texas 
Blossom infected with rosette fungus shown at right in , 
droto a b o ~  and ea lcft ia bottonr photo. 
Cover photo: Orange rust on "Humbk" v-. 
- ",J- 
DLACKBERRY DISEASES 
AND THEIR CONTROL 
George L. Philley and Leon R. Smith* 
Blackberries and dewberries often are attacked by 
a variety of disease-producing organisms. The major- 
ity of these are fungi, but severarspecies of nematodes 
and at least one virus may also 'weaken plants and 
reduce quality and yield of berries. The perennial na- 
ture of berry plants favors build-up of disease or- 
ganisms over a period of time, so  that the productive 
life of plantings often falls far short of expectations. An 
understanding of these diseases, the organisms that 
cause them and the conditions required for their de- 
velopment will help berry growers establish and main- 
tain healthy, productive plants. 
--Crown Gall 
Crown gall disease is caused by tumor-inciting 
bacteria present either in the soil at planting time or on 
propagative root cuttings. The disease can be recog- 
nized by the presence of galls or tumors on the roots 
or on the crowns either below or just above the soil 
line. Galls may range from pea-size or smaller up to 
several inches in diameter. Plants may be stunted or 
weakened by crown gall bacteria. This makes them 
susceptible to invasion by other soil organisms. 
Control of crown gall depends almost entirely on 
planting gall-free blackberries in clean soil. Avoid 
planting at old berry sites or where other host plants 
such as rose or fruit trees have been established pre- 
viously. 
*Extension plant pathologist and Extension agent-plant pathol- 
ogy (pest management), The Texas A&M University System. 
Crown g 8 Y  diuuc. 
Nematodes 
Several nematode species are parasitic to black- 
berries and dewberries. Soil populations of these 
parasites may increase considerably a s  plants age, re- 
sulting in dwarfed fruiting canes and smaller fruit. 
Damage generally is most severe in light, sandy soils. 
During hot summer months or under severe moisture 
stress, foliage of heavily infested plants may turn 
yellow and drop early. 
A practical approach to nematode control in com- 
mercial fields and in home gardens consists of plant- 
ing clean root cuttings in soil where only grasses or 
small grains have been allowed to grow for 3 to 4 
years. In the absence of suitably clean land, soil may 
be treated with an approved pre-plant soil fumigant  to^ 
reduce nematode populations to acceptable levels. 
2 .  
Anthracnsse, sometimes called dieback, is a 
common foliage and cane disease of blackberries and 
is first noticeable in the spring 
on new shoots and a s  purple- 
bordered spots an h u e s .  As spots on canes enlarge, 
shape and gradually turn gray. 
dry out, crack, and cane tips die 
ome white with age, and affected 
out leaving a shot-hole effect. 
The c a d  fungus also attacks fruit, resulting in small, 
dry, scabby berries. Certain berry varieties, such as 
Boysen, Young and Ness, are very susceptible to an- 
thracnose; Brazos is moderately susceptible; and 
mect types, such a s  Humble, Lawton and Cherokee, 
.8re least affected by the disease. 
Anthracnose control on susceptible varieties is 
accomplished by a combination of cultural practices 
chemical control. Before planting, destroy any 
the immediate area. In humid areas 
se is likely to cause greatest damage, 
ant varieties should be used. 
Plant at sites having good air movement, and 
space plants wide enough apart to permit good air 
circulation. For established plants, remove and bum 
bdl badly infested canes soon after harvest. Weed and 
grass growth in the row should be kept down for good 
eir circulation around plants. 
Chemical control of anthracnose on  susceptible 
varieties involves three to four fungicide spray appli- 
cations, beginning in early spring when leaf buds have 
swelled or are just beginning to open. Timing of the 
I first application is very important in preventing later 
buildup of the causal fungus. Use Captang, basic 
copper sulfate or lime sulfur, making sure all plant 
parts are covered thoroughly with spray material. 
Orange Rust 
Orange rust disease is caused by a fungus that 
moves systemically throughout infected plants, 
rendering them useless for future production. In com- 
, mercial production fields of East Texas, it is most 
1 serious on the Humble blackberry. 
This disease is recognized easily by the large mas- h ses of oran, colored spores produced in the spring L 
I Anthracnose cane lesions. 
on the leaves of affected plants. As leaf expansion is 
completed in late March or early April, large orange 
pustules form on the undersides of leaves, often caus- 
ing distortion and upward leaf rolling. The pustules 
rupture and release spores for a period of about 60 
days. Rust symptoms then disappear, but foli; 
remains sickly in appearance. All new canes produc- 
on affected plants will be non-productive. 
Control of orange rust is limited to cultural prac- 
tices that prevent spread of the disease and the use of 
resistant varieties. Remove all infested plants, includ- 
ing complete root systems, as  soon as pustules be- 
come noticeable in the spring and before spores are 
released. Fungicidal sprays have not provided satis- 
factory control. Boysen, Eldorado, Lawt on and 
Young varieties are resistant to orange rust disease. 
Brazos is practically immune. 
Rosette 
Rosette, also known as  double-blossom or witch's 
broom, is another fungal disease that prevents normal 
fruit development. Both wild and cultivated black- 
berries and dewberries are susceptible. Observations 
made at the Overton Research and Extension Center 
indicate varieties differ in their susceptibility to 
rosette. Humble has high resistance, whereas 
Comanche and Cheyenne are very susceptible. 
Cherokee, Bryson and Womack are moderately sus- 
ceptible. Brazos and Rosborough are moderately re- 
sistant. Varietal resistance may not be permanent be- 
cause there have been recent reports of an increase in 
rosette on the Brazos variety in Southeast Texas. 
Symptoms of rosette are short, broom-like clus- 
ters of foliage arising from infected canes. Flower buds 
on infected canes may appear somewhat larger and 
redder than normal. At flowering, petals may appear 
wrinkled or distorted, and sepals of the bract much 
elongated. Blossoms on infected canes, or blossoms 
recently infected by aerial spores of the fungus, fail to 
make fruit. On damp mornings, close examination will 
reveal a network of light gray fungal growth on af- 
fected flower parts. 
Control of rosette requires removing affected 
canes a s  soon as  they become noticeable. Destroy all 
wild berry plants in the vicinity. Remove and burn all 
fruiting canes soon after harvest and keep plants 
adequately spaced for good air circulation. Where 
heavy infection has occurred, mowing all canes to the 
ground may be necessary. Do this soon after har- 
low production of new canes for the next 
other than those caused by the an- 
fall. On rare occa- 
reserve foliage and 
disease is caused by a virus. Infected 
urces of virus infection. Removing infected 
d roots and destroying wild brambles will re- 
ead of the virus to healthy plants. Obtain 
blackberry plants from reputable sources where 
sterility disease is not a problem. 
Conclusion 
Good cultural practices play an important role in 
blackberry disease control : 
1. When possible, select varieties with resistance 
to diseases common in your area. 
2. Examine roots before planting to ensure ab- 
sence of crown gall. 
3. Do not propagate cuttings from diseased 
plants. 
4. Choose planting sites with good air circulation. 
5. Destroy all wild berry plants and brambles inl 
nearby fence rows or in the vicinity of the plant- 
ing site. 
6. After harvest, remove and burn the old fruit 
canes and any new canes that appear diseased. 
7. Thin healthy canes for good air circulation, and 
prevent excessive weed growth in the rows. 
Educational programs conducted by the Texas  Agricultural Exten- 
sion Service serve people of all ages  regardless o j  socioeconomic 
level, race ,  color, sex,  religion o r  national origin. 
Cooperative Extension Work in Agriculture and Home Economics, 
The  Texas  A&M University System and the United States Depart- 
ment of Agriculture cooperating. Distributed in furtherance of the 
Acts of Congress  of May 8. 1914, as amended, and June 30. 1914. 
10M - 3-82. Revision PP Rr HORT 2- 1 


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Blackberry Diseases and Their Control.

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Texas A&M Repository

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Blackberry Diseases and Their Control.

Abstract

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Full text

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Texas A&amp;M Repository

Texas A&M University

Texas A&M Repository