SPUR BLIGHT ON RASPBERRY
(adapted from Cornell Extension)
A common disease of red raspberry is spur blight, caused by the fungus Didymella applanata. It is specific to raspberries (Rubus spp.) and red raspberry appears to be the most susceptible. Infection begins at the margins of the oldest leaves on primocanes. The fungus progresses towards the mid-vein and produces a brown V-shaped lesion with a broad yellow margin. By mid-June and July, the fungus travels through the leaf and petiole and invades the cane. On the cane, symptoms are centered around individual buds and appears as a dark purple to chestnut brown blotches by mid-summer. The infected leaves drop soon after. Symptoms are first noticeable at nodes towards the bottom of the cane in early summer and progress to nodes located higher up on the cane as the season progresses, usually only the lower third to half of the primocane is affected. The axillary buds are generally not killed, but may be smaller and are prone to winter injury and stunted growth the following spring.
Spur blight lesions become difficult to detect late in the fall once the primocanes mature and develop their bark. In the winter, affected canes develop a silver or gray appearance around the lesions, and small black pimple-like structure (pycnidia) pepper the affected region. Buds at affected nodes may fail to grow in the spring or produce apparently healthy lateral shoots that develop fewer blossoms in spring. There are several options to help minimize the incidence and/or the impact of spur blight. The first is pruning. Growers should narrow rows so that the overall width does not exceed 12 to 15 inches. This will open up the canopy, allowing good air circulation to facilitate the rapid drying of leaf surfaces as well as allowing better penetration. Controlling weeds and removing cane suckers also improves air movement.
Pruning to remove diseased canes is important because these serve as the source of new infections next season. Severely diseased canes should be pruned in the fall, when symptoms are evident, removed from the planting and burned. For fall-bearing varieties, disease pressure is greatly reduced when all overwintering canes are removed and burned. Growers also can reduce spur blight by variety selection. Royalty, Titan, Canby, Skeena, Willamette, Reveille, and Sentry are particularly susceptible to the disease; Boyne, Brandywine, Killarny, Latham, and Newburgh are less susceptible. The fall bearing variety Heritage is also susceptible.
The delayed-dormant application of lime sulfur in the spring is recommended as a means to burn out existing, overwintering lesions (this spray is not needed in fall bearing varieties that get mowed over). This spray can be very effective at reducing the incidence of disease in well-weeded and pruned plantings.
SPECIALIST TO LEAD MUMMY BERRY WORKSHOP NOVEMBER 8
(from NH Extension)
Due to the increasing occurrence of blueberry mummy berry disease on farms in the region, growers may be interested in attending a workshop with a nationally-recognized expert in small fruit diseases. Dr. Annemiek Schilder is an Assistant Professor in the Department of Botany and Plant Pathology from Michigan State University. She has conducted extensive field research and trails on blueberry diseases. On November 8 at 6:00 p.m, she will present an overview of mummy berry disease management strategies and fungicide options to blueberry growers. The program is intended to train growers on disease development, disease monitoring, cultural and managerial practices to control the diseases along with proper pesticide use and timing of applications in order to reduce the disease occurrence. The meeting will take place at the UNH Cooperative Extension - Hillsborough County Office, 329 Mast Road (Route 114), Goffstown, NH. This seminar is being partially funded through the New Hampshire Department of Agriculture, Markets and Foods - Integrated Pest Management Grant Program. For more information contact George Hamilton at: (603)641-6060 or: email@example.com
PRACTICES THAT MINIMIZE NITRATE LEACHING
(adapted from Cornell Extension)
Good nitrogen management not only prevents pollution, it saves
money. A variety of practices, in both spring and fall, can help keep excess
nitrogen from leaching out of soil as nitrate.
1. Take soil tests on a regular basis and follow university guidelines when applying fertilizers.
2. Account for the N contributions from legume, grass sod, manure and soil organic matter.
3. Establish winter hardy cover crops after cash crops, especially if manure is applied in the fall.
4. Limit fall manure applications to no more than 50% of the N need of the next crop.
5. Spread manure at least 100 feet away from wellheads, springs or surface waters.
6. Avoid spreading manure before heavy rainfall.
7. If possible, disturb soil cracks with tillage before or during manure applications.
8. Use little or no manure after plowing down of a good sod stand.
9. Kill sod crops as late in the fall as possible, especially if it’s a heavy alfalfa stand.
10. Minimize the use of N in starter fertilizer since crop demand is low early in the season.
11. Apply all N sources as close as possible to the time of greatest plant needs by sidedressing.
12. Use the pre-sidedress (June) nitrate test on full-season crops to guide side-dress N decisions.
13. Maintain accurate records on rotations, fertilizer and manure applications, and crop yields.
SALVAGING GOOD PUMPKINS FROM A FIELD WITH PHYTOPHTHORA
(from UMass Extension)
Harvest healthy-appearing fruit as soon as they are ready. Harvesting after several days without rain or irrigation is ideal because fruit without symptoms are most likely not infected. A final fungicide treatment of copper and/or Bravo may be worthwhile to protect the fruit. Fruit can be removed from plants and put in rows for treatment; this will reduce the amount of fungicide needed and spray coverage will be improved. Treating fruit with Clorox or hydrogen peroxide can kill Phytophthora spores that have not started to infect the fruit. These materials have no residual activity and thus will not protect the fruit from spores that land on the fruit after treatment, in contrast with fungicides. Fruit should be removed from the field as soon as possible, especially if rain is forecast. Examine harvested fruit daily for symptoms; immediately dispose of affected fruit to minimize spread to other fruit. In Cornell experiments examining several postharvest treatments, removing fruit from the field had the greatest impact. Even fruit removed and put in another field on straw had much less disease then those left in the infested field.
THINGS NOT TO DO WITH PERENNIAL WEEDS
(adapted from Wisconsin Extension)
1. Ignore small patches of whatever. Many times I have heard that
"a few years ago it was just in the corner of the field” ...that’s when
controls are most effective.
2. Misidentify them. The grower said “It looked like a grass” and they really had yellow nutsedge. Today you might think you have quackgrass and it’s wirestem muhly. Or you thought it was bull thistle in the pasture and it was Canada thistle. Know the enemy.
3. Let them go to seed. Most perennials can come at us via seeds as well as vegetatively.
4. Let them have the fence-rows. If you do, be sure you keep an eye on them and know when they start to spread. Or pay attention when the neighbors tell you they’re moving!
5. Think that cultivation has no impact on them. Perennials can be set back considerably by tillage; when used in combination with herbicides we often get the best effect, especially in corn.
6. Spread propagules on tillage or harvest equipment. The propagules to be aware of are root segments, tubers, rhizomes, and of course, seeds. Spreading these on equipment is all to easy to
do, especially during the spring rush to get from field to field.
7. Fail to map where they are. No map means you might miss treating some patches of perennial weeds this year and also it leaves only your memory and best guess as to where to
look next year and beyond to see if the infestation is still present.
COVER CROP TRIAL UPDATE
Our plots of 20 different cover crops at the Brattleboro Extension office look better than ever. Most have put on a lot of growth since our field day in early August. The May-sown cowpeas, soybeans, and hairy vetch plots are providing almost complete weed control at this point, and the yellow sweet clover and red clover/Sudangrass mix are also doing a good job of smothering in this weedy field. We tried a couple of new a new legume crops for us: sesbania has come in strong in the last month, now over 3 feet tall, but the berseem clover is much shorter and less vigorous and has not suppressed weeds as well. The field is gravelly and low in fertility so the non-legumes like Sudangrass and pearl millet are rather pale and not as vigorous as they would be on a better soil. We spread about 30 lb/A of N on half the pearl millet plot in August and the biomass in that area is now twice that in the unfertilized half. Forage samples have been sent to the lab to determine total N and dry matter yields. Stay tuned for a full report this winter.
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