Saturday, January 21, 2012
Small Fruit Viruses
Dr. Ioannis Tzanetakis with the University of Arkansas has written an excellent article illustrating the status and implications of emerging small fruit virus diseases in the US. This APSnet post is one among many fascinating on-line articles published by the American Phytopathological Society (APS).
Friday, December 2, 2011
Summary -- 2011 NC Blueberry Season
The 2011 North Carolina blueberry crop was of excellent quality due to the combination of a dry harvest season and good labor availability, which allowed growers to harvest top-quality fruit in a timely fashion. Most growers began harvesting around 16 May, with the bulk of the crop a few days early overall. Total volume was slightly reduced compared to the previous year, due to weather. The primary weather-related causes of loss were poor pollination in late March/early April, and drought during June and July.
In southeastern NC, cool, wet weather for an eight-day period (25 Mar to 1 Apr) decreased bee activity and thus pollination success of flowers that were blooming during that time, and reduced the volume of fruit on ‘Croatan’ and other cultivars in the same flowering period. In late April, small, unexpanded berries that had not been adequately pollinated were falling off the bushes at many locations. Not all fields were affected to the same degree, because bloom times vary by location and cultivar.
A drought from late May through July resulted in some shriveled fruit and loss of berry size, which accounts in part for the slight reduction in overall yield for the state. The drought was a real challenge -- most growers have irrigation, and with near-constant watering were able to keep fields from getting too dry; however fields without irrigation were severely affected and some bushes were lost.
Price and volume data were obtained from eight major shippers in the 2011 season. The first price reported for flats of 12-1 pint cups with lids was on May 17. Prices ranged mostly $20.50-$22.00. The last f.o.b. price report was issued on July 08 at $16.00. Approximately 29 million pounds, an equivalent of 3.2 million 12 1-pint flats, were shipped for fresh market. There was also an additional 7.7 million pounds processed (frozen). This total (fresh + processed) of 36.7 million pounds represents a record volume of berries harvested for fresh sales, a reduced volume of processed berries (frozen), and a slight reduction in overall pounds for the state.
Price and volume data provided by Karrie Gonzalez, NC Market News
In southeastern NC, cool, wet weather for an eight-day period (25 Mar to 1 Apr) decreased bee activity and thus pollination success of flowers that were blooming during that time, and reduced the volume of fruit on ‘Croatan’ and other cultivars in the same flowering period. In late April, small, unexpanded berries that had not been adequately pollinated were falling off the bushes at many locations. Not all fields were affected to the same degree, because bloom times vary by location and cultivar.
A drought from late May through July resulted in some shriveled fruit and loss of berry size, which accounts in part for the slight reduction in overall yield for the state. The drought was a real challenge -- most growers have irrigation, and with near-constant watering were able to keep fields from getting too dry; however fields without irrigation were severely affected and some bushes were lost.
Price and volume data were obtained from eight major shippers in the 2011 season. The first price reported for flats of 12-1 pint cups with lids was on May 17. Prices ranged mostly $20.50-$22.00. The last f.o.b. price report was issued on July 08 at $16.00. Approximately 29 million pounds, an equivalent of 3.2 million 12 1-pint flats, were shipped for fresh market. There was also an additional 7.7 million pounds processed (frozen). This total (fresh + processed) of 36.7 million pounds represents a record volume of berries harvested for fresh sales, a reduced volume of processed berries (frozen), and a slight reduction in overall pounds for the state.
Price and volume data provided by Karrie Gonzalez, NC Market News
Wednesday, November 30, 2011
10th International Vaccinium Symposium
On behalf of the Vaccinium Species Working Group, Vine and Berry Fruits Section of the International Society for Horticultural Science (ISHS), the conveners and organizing committee invite you to attend the10th International Vaccinium Symposium, to be held June 17-22, 2012 in Maastricht, Province of Limburg, The Netherlands. The meeting is being held in conjunction with the Floriade 2012 World Horticultural Expo: http://www.floriade.nl/
For more information or to contact the conveners, please visit the symposium website: http://www.vaccinium2012.com/
I look forward to seeing you in Maastricht!
Bill Cline, Chair
ISHS Vaccinium Working Group
For more information or to contact the conveners, please visit the symposium website: http://www.vaccinium2012.com/
I look forward to seeing you in Maastricht!
Bill Cline, Chair
ISHS Vaccinium Working Group
2012 Blueberry Open House and Trade Show
The 46th Annual Open House of the North Carolina Blueberry Council is coming up on January 10th and 11th, 2012. The meeting will be held at the Sampson Agri-Exposition Center in Clinton, NC at 414 Warsaw Road near the intersection of Hwy 24 and Hwy 701 business. For more information or to preregister, Contact Julie Woodcock at (910) 471-3193, or email ncblueberry@bellsouth.net
Thursday, October 6, 2011
Evaluating leafspot effects
Late September is a good time of year to evaluate the effects of leaf spot diseases. If most of your leaves are still attached to the bush at this time of year, then most likely flower bud formation has occurred and the crop potential for next year is good. If, however, your leaves have already detached by the end of September, then chances are that some flower buds did not form due to premature defoliation, and crop potential for next year has already been reduced.
The image below shows three twigs from the cultivar Star, collected on 30 Sep 2011. Star is susceptible to Septoria leaf spot caused by the fungus Septoria albopunctata. These are older twigs from the first flush of leafy growth in spring, and by now should have formed visible flower buds at the base of each leaf.
The shoot on the left is from a bush that was protected with a fungicide, retained its leaves, and has formed 5-6 flower buds. The unprotected shoot in the middle defoliated early, and by comparison formed only a couple of flower buds at the tip. The shoot on the far right was also defoliated early, not by leaf spots but by hurricane Irene. It too, has only one or two flower buds. Note that the shoot defoliated by hurricane winds still has the leaf petioles (bases) attached -- the leaves did not abscise normally, but were torn away: This also happens (leaves missing, but petioles still attached) with caterpillar feeding damage.
Regardless of the cause, when the leaves are taken away too early, flower buds do not form, and the potential crop is reduced for the following year -- because fewer flower buds means fewer berries.
The two main fungal leaf spot diseases that cause defoliation on blueberries in North Carolina are Septoria leaf spot caused by Septoria albopunctata, and Anthracnose leaf spot, caused by Gloeosporium minus. The two diseases have very different symptoms, as shown below:
Anthracnose leaf spot, shown above, consists of large lesions that often occur at the edge of the leaf. Examples of susceptible cultivars are Pender (shown) and Duke.
Septoria leaf spot, by comparison, produces dozens of small lesions on each leaf. The southern highbush cultivar Star (shown) is very susceptible.
By evaluating leaf drop at this time each year, growers can get a good idea of how much disease pressure they have on their farm, whether fungicide use is warranted, and which cultivars are susceptible.
The image below shows three twigs from the cultivar Star, collected on 30 Sep 2011. Star is susceptible to Septoria leaf spot caused by the fungus Septoria albopunctata. These are older twigs from the first flush of leafy growth in spring, and by now should have formed visible flower buds at the base of each leaf.
The shoot on the left is from a bush that was protected with a fungicide, retained its leaves, and has formed 5-6 flower buds. The unprotected shoot in the middle defoliated early, and by comparison formed only a couple of flower buds at the tip. The shoot on the far right was also defoliated early, not by leaf spots but by hurricane Irene. It too, has only one or two flower buds. Note that the shoot defoliated by hurricane winds still has the leaf petioles (bases) attached -- the leaves did not abscise normally, but were torn away: This also happens (leaves missing, but petioles still attached) with caterpillar feeding damage.
Regardless of the cause, when the leaves are taken away too early, flower buds do not form, and the potential crop is reduced for the following year -- because fewer flower buds means fewer berries.
The two main fungal leaf spot diseases that cause defoliation on blueberries in North Carolina are Septoria leaf spot caused by Septoria albopunctata, and Anthracnose leaf spot, caused by Gloeosporium minus. The two diseases have very different symptoms, as shown below:
 |
| Anthracnose leaf spot (Gloeosporium minus) |
 | ||
| Septoria leaf spot (Septoria albopunctata) |
By evaluating leaf drop at this time each year, growers can get a good idea of how much disease pressure they have on their farm, whether fungicide use is warranted, and which cultivars are susceptible.
Tuesday, September 27, 2011
Cylindrocladium blight
Cylindrocladium blight is a disease caused by a plant pathogenic fungus. Infection results in leaf spots, brown, dead stems, and often dead plants. On blueberry it is a disease of propagation and nursery beds, and is rarely seen on plants in the field. Symptoms commonly appear in blueberry rooting beds in the late summer and into fall. The disease may also occur in potted plants that are spaced too close together in pot yards. One species of this particular fungus also infects peanut plants in the field, so blueberry propagators in North Carolina often call the disease "peanut blight". There are many species of Cylindrocladium that infect plants, and there may be more than one species of this fungus causing disease in blueberry rooting beds. At present the only species reported on blueberry in North Carolina is now considered to be Cylindrocladium parasiticum, hence the common name of the disease, Cylindrocladium blight.
The disease is most often seen in propagation beds and pot yards that have grown vigorously and are too dense to allow proper air movement between plants. Spores of the fungus infect leaves and stems, and eventually kill entire plants. Often the root system is the last healthy part remaining. The phenomenon of plants dying in the center of a dense block, while those at the edge (with better air circulation) survive, is characteristic of this disease in dense beds of plants.
In pot yards and late-stage propagation beds where the plants have already formed roots, this disease is best managed by not over-watering or over-fertilizing plants, and by maintaining proper plant spacing so that the leaves and stems can dry between waterings. Cull to remove and discard any dead plants, and space the remaining plants out as much as possible so that there is good air movement between the bushes. Do not re-use any old used potting media, as this disease can carry over from one year to the next in contaminated soil or potting mix. Clean up as much debris as possible and sanitize the bed area and any pots that you plan to re-use.
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| Cylindrocladium blight in a bed of softwood cuttings in late fall. |
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| Closeup of orange fungal fruiting bodies on an infected cutting |
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| Irregular-shaped spots on lower leaves of older rooted cuttings |
The disease is most often seen in propagation beds and pot yards that have grown vigorously and are too dense to allow proper air movement between plants. Spores of the fungus infect leaves and stems, and eventually kill entire plants. Often the root system is the last healthy part remaining. The phenomenon of plants dying in the center of a dense block, while those at the edge (with better air circulation) survive, is characteristic of this disease in dense beds of plants.
 |
| Large area of dead plants in a propagation bed late in the season |
In pot yards and late-stage propagation beds where the plants have already formed roots, this disease is best managed by not over-watering or over-fertilizing plants, and by maintaining proper plant spacing so that the leaves and stems can dry between waterings. Cull to remove and discard any dead plants, and space the remaining plants out as much as possible so that there is good air movement between the bushes. Do not re-use any old used potting media, as this disease can carry over from one year to the next in contaminated soil or potting mix. Clean up as much debris as possible and sanitize the bed area and any pots that you plan to re-use.
Tuesday, August 23, 2011
Blueberry Stem Canker
Blueberry stem canker caused by the fungus Botryosphaeria corticis is common on cultivated and wild blueberries in North Carolina. The disease spreads by spores and through the use of infected cutting wood for propagation. Canker is important because it can weaken and kill susceptible or stressed bushes.
Symptoms: Cankers are noticeably thicker than adjacent portions of the stem, forming raised areas with deep cracks. Usually only short sections of the stem are affected, though canes of some very susceptible cultivars can have multiple infection points along their entire length.
Disease cycle: Infection of stems is by spores (ascospores and conidia) that are released during wet weather and disseminated by wind from April through September. Young, succulent, actively growing shoots are infected, and symptoms appear within 4 to 6 months after infection. As the fungus continues to grow and invade the wood, large cankers with deep fissures and cracks develop that girdle, weaken and kill the stem.
Control: Fungicides are partially effective but not practical. Control relies on maintaining general plant health,
pruning to remove canker-weakened canes,use of resistant cultivars, and use of disease-free planting stock. Cutting wood should be selected from undiseased plants, or the plants sourced from disease-free nurseries. In areas where canker is not present, the use of disease-free planting stock is critical to avoid introducing this pathogen to an new field.
Highbush blueberry: Among the popular southern highbush cultivars (Vaccinium corymbosum) grown in eastern NC, O'Neal, Blueridge and Legacy are susceptible -- however all three are successfully grown where plant health is maintained via proper site selection, fertility, pruning and irrigation.
Rabbiteye blueberry: Cankers can be numerous on rabbiteye blueberries (Vaccinium virgatum, synonym V. ashei) but generally do not cause yield loss on this vigorous blueberry species.
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| 'O'Neal' canes dying out due to canker infections |
Symptoms: Cankers are noticeably thicker than adjacent portions of the stem, forming raised areas with deep cracks. Usually only short sections of the stem are affected, though canes of some very susceptible cultivars can have multiple infection points along their entire length.
 |
| Swollen area (at center) with deep cracks is a fully developed canker |
Disease cycle: Infection of stems is by spores (ascospores and conidia) that are released during wet weather and disseminated by wind from April through September. Young, succulent, actively growing shoots are infected, and symptoms appear within 4 to 6 months after infection. As the fungus continues to grow and invade the wood, large cankers with deep fissures and cracks develop that girdle, weaken and kill the stem.
 |
| Cankers on a young stem, exuding spores |
Control: Fungicides are partially effective but not practical. Control relies on maintaining general plant health,
pruning to remove canker-weakened canes,use of resistant cultivars, and use of disease-free planting stock. Cutting wood should be selected from undiseased plants, or the plants sourced from disease-free nurseries. In areas where canker is not present, the use of disease-free planting stock is critical to avoid introducing this pathogen to an new field.
Highbush blueberry: Among the popular southern highbush cultivars (Vaccinium corymbosum) grown in eastern NC, O'Neal, Blueridge and Legacy are susceptible -- however all three are successfully grown where plant health is maintained via proper site selection, fertility, pruning and irrigation.
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| Cankers on a one-year-old 'Legacy' stem |
Rabbiteye blueberry: Cankers can be numerous on rabbiteye blueberries (Vaccinium virgatum, synonym V. ashei) but generally do not cause yield loss on this vigorous blueberry species.
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