Monday, July 27, 2009

Blueberry School: Valdensinia leaf spot

Blueberry Hill Farm Headquarters conference room
Wednesday July 29th 6pm to 7pm
Dr. Seanna Annis

Session will demonstrate how to identify the new Valdensinia leaf spot from other leaf spots. Samples with the disease will be on hand for people to look at. Scouting and treatment recommendations will be discussed.

Please bring to the meeting any leaf spot samples (in a sealed plastic bag) you want identified.

Remember: when collecting samples, do not go into a wet field and remove all leaves from your footwear, clothes, and vehicles before leaving the diseased area.

Estimated Water Budget July 20 to July 26

More than enough rain yet again for this past week.


Wednesday, July 22, 2009

Sanitation to Protect Fields from Valdensinia leaf drop Disease

There is NO tested fungicide that will eradicate this disease from a field. Fungicides will only suppress the disease by protecting the plants. Once in a field, the fungus will produce new spores and infect plants after any 3 day wet period throughout the season. Many fungicide applications will be necessary throughout the prune and crop years to protect plants if this disease is in your field. We want to avoid the trouble (hopefully it is not a disaster) that is hitting growers in Nova Scotia this year from Valdensinia leaf drop disease.

THE KEY IS - DO NOT MOVE ANY DISEASED LEAVES AROUND
  • Do NOT walk or drive through any areas of leaf drop or brown leaf spots in a field. Do NOT harvest any area with suspected (or confirmed) Valdensinia leaf drop. Once, confirmed to have the disease, BURN any plants with Valdensinia leaf spot to the ground including burning all leaf litter, as soon as possible.
GENERAL PRECAUTIONS
  • At the edge of ANY field you visit, brush leaf litter off of your footwear and vehicle before going to another field. Brush off your footwear and vehicle tires with your hand or something that will NOT collect leaf litter. (If you use a brush, clean it off regularly).
  • ALL equipment, vehicles, ATVs, harvesters, blueberry boxes, etc. need to be cleaned off of leaf litter BEFORE they are moved out of a field. All equipment should have no leaf litter on it before you let it into your field. Spraying with a 5% bleach solution (1 part bleach to 19 parts water), other disinfectant or a weak soap solution may help to remove the leaf litter, but may NOT kill the fungus (see below).
  • What will NOT WORK - Soaking infected leaves in 10% bleach solution for 1 ½ minutes did NOT kill the fungus! Just dipping footwear or spraying equipment with disinfectant or bleach solution will NOT work, UNLESS the leaf litter is removed.
Please contact Seanna Annis at the Blueberry Hotline (1-800-897-0757) if you have any questions.

Tuesday, July 21, 2009

UMaine Sustainable Agriculture Field Day July 27

STILLWATER, Me. —University of Maine Cooperative Extension will host its annual Sustainable Agriculture Field Day on Monday, July 27. Designed for farmers, crop advisers and other members of the agricultural community, the event will take place at Rogers Farm, UMaine's 100-acre forage and crops research facility, located on Bennoch Road in Stillwater. Registration will begin at 9 a.m., and events will run until 12:30 p.m. This free event will feature talks on many agricultural topics. Participants will receive one pesticide certification credit and three Certified Crop Adviser credits. For more information,contact Ellen Mallory at 207-581-2942 or John Jemison at 207-581-3241.

UMaine agricultural researchers and Extension faculty members will present their field research on vegetables, grains, and forages. Specific topics will include bread wheat and specialty potato production issues, weed management tools for small-scale vegetable producers, organic fertilizers for sweet corn, and feed and forage rotations for organic dairies. Students from the Black Bear Food Guild will also talk about their community-supported agriculture project.

Presentations will be offered by: Eric Gallandt, associate professor of weed ecolog yand management; John Jemison, Extension water quality specialist; Rick Kersbergen, Extension educator in Waldo County; Lauren Kolb, graduate student in weed ecology; Ellen Mallory, Extension sustainable agriculture specialist; and Marianne Sarrantonio, associate professor of sustainable crop production, in addition to students and members of the Black Bear Food Guild.

EStimated Water Budget July 13-19

Thursday, July 16, 2009






Figures 1 and 2 (top and middle) Valdeninsia leaf spots of lowbush blueberry leaves. Figure 3 (bottom) Defoliated stems from loss of leaves infected with Valdeninsia

Valdensinia Leaf spot: NEW Disease in Maine Blueberry Fields

Update as of July 17th, 2009: Valdensinia leaf spot has been found in commercial blueberry fields in Sumner, Jonesport and Township 24. Please check your fields for this disease.

Valdensinia leaf spot (caused by Valdensinia heterodoxa) causes early leaf drop in lowbush blueberries and in prune fields can cause complete leaf drop so that no flower buds are produced by infected stems. By June 2009, Valdensinia leaf spot had caused complete defoliation in approximately 40 crop and prune fields in Nova Scotia, and had been found in Quebec and New Brunswick fields.

Valdensinia infects all clones of lowbush blueberry and both prune and crop plants. The spots are typically round, large and brown, and can have a “bull’s eye” appearance. Leaves can have from 1 to about 10 spots that can be from ⅛ to ½ inch and larger. These spots rapidly enlarge on the leaves and can spread from stem to stem within a few days. This leaf spot causes early leaf drop, and young leaves drop off when infected by only one spot and while still green. Stems can have complete leaf drop or only have a few infected leaves at the top of the stem. Older infected leaves will remain on the plant until leaf drop in the fall. In prune fields, stems with complete leaf drop will not produce flower buds for the next year. Crop fields with leaf drop will have decreased yields and smaller berries.

The fallen infected leaves are the source of new spores to cause more infections. The spores are large and very efficient at infecting blueberry leaves. The spores can be produced in 2 days on wet, dead infected leaves on the ground. Mature spores are shot off, up to 8 inches high, and typically land on the underside of leaves. The spores will attack all ages of blueberry leaves and will also try to infect all plants they land on so you may see small spots on nearby weeds. The fungus requires about 6 to 8 hours of wet weather (rain or fog) for the spores to infect new leaves. The disease will rapidly spread out from infected stems to adjacent plants as long as the leaf litter remains wet and there is occasionally wet weather for 6 to 8 hours. The fungus survives over the winter in infected leaves. In the spring, about the time of early bloom, it will produce new spores and then leaf infections during the first period of 3 days of wet weather.






Figure 4 (top). Dead leaves with thickened black middle veins where the fungus will survive over the winter. Figure 5 (bottom). Infected blueberries and attempted infections on other plants

Moving ONE dead leaf will spread this disease (see photos below). This disease spreads to new areas of a field and new fields by movement of dead, infected leaves on contaminated footwear, vehicles and equipment including blueberry boxes. NEVER enter a wet field suspected of or having this disease. The dead leaves are sticky and will cling to footwear, vehicles, equipment, boxes, etc. ALWAYS check your footwear for leaves and remove them before leaving any diseased area and do NOT move equipment or drive through diseased areas.








Figure 6 and 7 (top and middle right) A vehicle was driven through a diseased area (bottom of photos) and then driven through healthy areas produced new diseased stems along tire tracks. Figure 8 (bottom left). Walking through the original diseased area and then into healthy areas produced new infected stems in the grower’s footprints.

Precautions for ALL Blueberry Fields

Steam clean all equipment and vehicles before moving them between fields.

Clean blueberry boxes BEFORE they go into your field. Remove all dead leaves stuck to the boxes in a place away from your field and burn the leaf litter.

Key features to identify this disease:

- Large round spots, ⅛ to ½ inch and larger, often look ringed like a bull’s eye on leaves. Typically there are less than 10 spots per leaf, often only 1 to 4.

-Stems with leaf drop, particularly of lower leaves. Early in the season, young leaves will fall off while still green.


If you find this disease in your field

- Do not enter the field when it is wet, Remove dead leaves from your footwear before leaving the diseased area (so you do not spread it around the field)

- Flag off the infected area so no one walks through it or moves equipment through it

- Check your vehicles or other equipment that may have come in contact with the infected area for dead leaves. Steam clean all equipment and vehicles before moving them between fields.

- Contact Seanna Annis or Dave Yarborough to confirm and report disease (Blueberry Hotline: 1-800-897-0757)

- Once disease is confirmed follow treatment recommendations below.


Be careful to NOT move dead infected leaves around the field or between fields even after treatment.

For Prune fields: As soon as presence of the disease is confirmed, BURN the diseased area and a 10 ft area outside the edge of the infected stems with a hand-held burner or by placing straw on the infected area. Burn around edges of the area first, and then move into center of diseased area. You do not need to burn your whole field unless your whole field is affected by the disease. The diseased stems produce few, if any, flower buds for the crop year and burning early will help prevent spread of this disease to other areas in the field.

For Crop fields: Do NOT harvest areas with disease and do NOT move any equipment through diseased area. As soon as presence of the disease is confirmed, BURN the diseased area and a 10 ft area outside the edge of the infected stems with a hand-held burner or by placing straw on the infected area. Burn around edges of the area first, and then move into center of diseased area. You do not need to burn your whole field unless your whole field is affected by the disease.

In the Spring of Next Year: From early bloom on, check plants in infected field, particularly in the infected area, for leaf spots after the first period of 3 days of wet weather. If you see any leaf spots, apply the fungicide that will be recommended in 2010 Disease Control Guide for Wild Blueberries as soon as possible and before the next wet period.

Prepared by Dr. Seanna Annis, Blueberry Pathologist, School of Biology and Ecology, and Dr. David Yarborough, Extension Blueberry Specialist, University of Maine, Orono, ME, USA with information provided by Dr. Paul Hildebrand, Plant Pathologist, Atlantic Food and Horticulture Research Centre, Agricuture and Agri-Food Canada, 32 Main St. Kentville, NS, Canada

Monday, July 13, 2009

Estimated Water Budget July 2 to 12

Tensiometers at Jonesboro, Deblois and Northfield (all sandy loams) were all reading between 9 and 12 cb around 1 PM today. Heavy rains later this afternoon are likely to lower these readings to around 5 cb or so. So soils are still plenty moist as we end the second week of July. See you all at Blueberry Hill farm day this Wednesday.


Thursday, July 2, 2009

Estimated Water Budget June 25 to July 1, 2009

Soils were wet but not water logged at most of my study sites as of yesterday. Tensiometers at the sandy loam and loamy sand sites all read between 8-11 cb. At one lowland site in Northfield however the water table was within approximately 2 feet of the surface. This site has shown a propensity for flooding, likely due to it's elevation, proximity to a lake and relatively fine textured soil.

With respect to the precipitation recorded for Cherryfield, my rain gauge appears to be consistent with those posted online for the immediate vicinity.