Seasonal Tips

Answers to popular current questions from the Master Gardener Helpline (1-800-639-2230).

Regular updates of these 'Seasonal Tips' has been discontinued. Please check the archives for seasonal tips from past years. Many tips will apply from year-to-year.

Seasonal Tips archives: 2001-2007

Vermont Hardiness Zone Map (link to Perry's Perrenial Pages)
New England Hardiness Zone Map (link to UConn)

POSTED 7/31/09

Late Blight Press Release click here for article from Dr. Vern Grubinger, Vegetable and Berry Specialist, University of Vermont Extension (pdf)

POSTED 7/29/09

Burned by Wild Parsnip: click here for article from Wisconsin Department of Natural Resources

More facts about Late Blight
Ann Hazelrigg, Plant Diagnostic Clinic

1. Seems like the blight has gotten all around the state in the last storm, and is causing plants to die quickly.
2. Tomatoes seem to be hit worse, but I suspect potatoes will go down soon.
3. Spores are everywhere and pruning off foliage that is blighted will really have no effect because there are thousands just floating in the breeze! If it would
   become hot and dry, things would settle down and the new blights would slow, however, given our weather forecasts, we are likely to see more blighting.
4. IF gardeners don't see the blight in their plants, they could protect them with a fungicide (Bravo or coppers for organic)on a 5-7 day schedule but the these may
   not keep everything protected if inoculum is high and if some infections have already started.
5. Once the grower does have late blight, it will likely take out the whole crop. Best to pull up plants, put under a tarp so all dies quickly. Can also bag and
   landfill, or dig hole! Other options are to til under. Don't just leave plants standing because it will provide lots of inoculum for everyone else! The disease WILL
   NOT OVERWINTER on stakes, cages, on dead tissue, so that is good news for tomato growers. It will only be a problem next year if we have more storms that blow in
   spores, if we have contaminated plants brought in from the south, or if we have infected tubers that have overwintered. So, rotation is not that important for this
   disease in tomatoes, although it is for the other fungal diseases of tomatoes.
6. The only place the disease can overwinter is on infected tubers. SO if potatoes still look fine (as many do) protect with copper or other fungicide if they want.
   If the disease does get started in the potatoes, mow the plants BEFORE it gets very widespread, let all the tissue die (so spores die) and allow tubers to
   harden/suberize for a week and then harvest. If the plants were allowed to just become really blighted, there could be alot of stem cankers and this could grow down
   to the tubers and infect them. YOU DO NOT WANT THIS TO HAPPEN, so mow when disease gets started and all should be fine. Tubers may be a little smaller but they should
   be ok. Discard any that look bad at harvest.

POSTED 7/22/09

Wild Parsnip: click here for factsheet from USDA Forest Service (pdf)

POSTED 7/7/09

Management for Tomato Fungal Diseases-2009
Ann Hazelrigg, Plant Diagnostic Clinic

With this rainy cool weather, several fungal diseases on tomatoes (and other crops) are going to be causing problems in the garden. Here are list of the common diseases you may encounter and some recommendations for management. I have included both organic and conventional options.

Late blight on tomato and potato -This has been in the news a lot lately due to the distribution of infected transplants throughout NE from some of the big box retailers. This disease often shows up in Vermont but not usually until much later in the season, so the early appearance has the potential for wiping out entire crops. Coupled with the wet cool weather, it makes perfect conditions for a rapid blighting and death of the plants. The inoculum (spores) are out there and are very easily moved on air currents. If we continue to have this perfect disease weather, it will spread throughout the state. If the weather turns warm and dry, the disease will not become as large a problem.

Symptoms-large half dollar size spot on the foliage (not necessarily on the lower leaves) that is greasy black/green. When humidity is high or it is wet, you will see white sporulation on the leaf undersides. For pictures:
http://vegetablemdonline.ppath.cornell.edu/DiagnosticKeys/TomLeaf/Late_Tom.htm

Management options-SCOUT your GARDEN!

• Bag infected plants and discard. If left in the garden, they will just provide inoculum (spores) for your neighbor’s tomatoes and potatoes. DO NOT COMPOST the tissue.
• Protect your remaining plants with a fungicide. The fungicide needs to be applied now and continued as long as the weather is conducive for disease and the disease is active. This requires a 5-7 day spray schedule with fixed coppers (Champ WG (NuFarm Americas. Inc.) and Nu Cop® 50 WP) for organic gardeners. Copper acts as a protectant on the plant. The better coverage with copper on the new growth and the rest of the plant, the better the chance you have of avoiding late blight. You need to repeat the spray since there is new unprotected growth daily on tomatoes and the copper will weather off with repeated storms and sunlight.
• For conventional gardeners use a 7 day spray schedule with using the fungicide Chlorothalonil (Bravo.) will be effective.

Early Blight and Septoria Leafspot - These fungal diseases will also start showing up as a result of the wet cool weather. The leafspots from these fungi will appear on the lower leaves first where the air circulation is poorest. Early blight has a larger leafspot with a target shaped appearance and Septoria causes a smaller spot that is gray with a whitish center. These diseases can build up over the summer and cause defoliation by the end of the summer. We typically see this to some extent every summer, unlike late blight.
For pictures:
http://vegetablemdonline.ppath.cornell.edu/DiagnosticKeys/TomLeaf/Early_Tom.htm
http://vegetablemdonline.ppath.cornell.edu/DiagnosticKeys/TomLeaf/Septoria_Tom.htm

Management:

• Stake tomatoes, use mulch to prevent splash up from soil.
• Keep up the vigor of your plants to better withstand the disease.
• Rotate tomato growing areas.
• Fungicides: These diseases can be controlled by using the same fungicides (fixed copper or chlorothalonil) as described for late blight. Sprays would need to be repeated every 7-10 days for the chlorothalonil and every 5-7 days for the fixed coppers depending on the weather pressure (shorten the time between sprays if there is a lot of rain, ie 5 days for copper and 7 for chlorothalonil)
  

POSTED 4/11/08

The last few days it seems that winter may finally be losing its grip on the garden. Here in Burlington the spring bulbs are pushing leaves through warming but still-firm soil. It won’t be long now! While we await the true arrival of spring, a few ideas for things to do indoors and out as the weather permits:

-If you haven’t already, this is a good time to have lawn and garden soil tested. Call the Master Gardener Helpline at 1-800-639-2230, or 656-5421 within Chittenden County, to request a test kit.

-Check on stored roots of tender perennials which you lifted last fall. Remove parts which appear damaged or diseased, and add a few drops of water to the storage medium if roots appear wrinkled or withered.

-Carefully examine houseplants for the presence of insects. Mealybugs or soft scales excrete honeydew, plant sap which forms a sticky residue on leaves and adjacent surfaces. These pests can be removed with a cotton swab dipped in rubbing alcohol, or controlled with an application of appropriately labeled horticultural oil. Fungus gnats are small dark flies which breed and feed on moist planting medium, especially “soil-less” mixes high in peat. Their presence suggests overwatering; allowing potting mix to dry out between waterings should provide control. With the start of a new growing season, resume periodic feeding with a dilute fertilizer.

-Most ornamental trees and shrubs can still be pruned now, before new growth begins. Remove dead, diseased, or damaged branches. This is a good time to make shaping and cosmetic cuts, as it may be easier to visualize the desired form when the branches are bare of leaves. Don’t use paint or wound dressing on pruning cuts as these can delay healing. Any sap bleeding from pruning cuts will not damage the tree. Delay pruning of spring-flowering trees and shrubs until after flowering to avoid reducing the display. Check the following link for a comprehensive discussion of pruning: http://extension.umd.edu/publications/PDFs/EB150.pdf

-While doing your late season pruning, inspect susceptible viburnum species for viburnum leaf beetle egg deposition sites. These appear as a row of raised bumps along the underside of last season’s growth. Prune out and destroy affected twigs.

-Plan now for a healthy lawn. Maintaining thick robust turf is the best way to control weeds. Though late summer is the best time for turfgrass establishment, you can overseed in the spring to fill in bare or thin areas before they are colonized by weeds. Lightly cultivate the area to be seeded, scatter seed and firm the soil to provide good seed-to-soil contact, cover loosely with straw and keep moist until seedlings emerge. Resist the temptation to fertilize heavily in spring; save fertilization for fall based on soil test results. If you had a problem with crabgrass last year, preemergent controls (“crabgrass preventers”) can be applied before the forsythia blossoms fall. Most preemergents will also interfere with turfgrass seed germination, so if you’re overseeding either avoid applying the crabgrass preventer to the seeded areas or purchase a product specifically labeled for newly seeded lawns.

-Continue starting vegetable and flower seeds indoors, planning to set them out in the garden when frost danger is passed. Peas and lettuce can be sown outdoors as soon as the soil is dry enough to work. Squeeze a handful of soil into a ball and bounce it on your hand- if the ball breaks apart it’s OK to till.

-Organic mulches are used in ornamental beds to provide a decorative soil cover, suppress weeds and conserve moisture. Apply mulch no more than 2 inches deep and keep it pulled back from the trunks of trees ands shrubs to discourage disease and feeding damage from insects and rodents.

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