Seasonal Tips

Answers to popular current questions from the Master Gardener Helpline (1-800-639-2230).
A link is made to those UVM Extension leaflets (EL,GD,etc.) available on the web. All leaflets are available through mail order or in person from UVM Extension offices (see theirPublications Catalog).

Vermont Hardiness Zone Map (link to UVM Extension)
New England Hardiness Zone Map (link to UConn)

new.gif (147 bytes)POSTED 6/23/03

Application of manure may encourage potato scab problems. With heavy rains, supplemental sidedressing may be needed, but no N should be applied after plants are 8-10 inches high. To control potato scab, maintain the soil pH around 5.3 or plant scab-resistant varieties. Sulfur can be used to acidify soil if necessary. If soil pH is much less than 5, a light application of lime may be advisable. If you are adding large amounts of home-made manure or compost, less fertilizer will be needed.

Well-rotted manure can meet N requirements. If growing hybrid varieties, increase all fertilizer application rates by 50%. Nutrients are added after cutting to promote healthy fern growth the following year. Do not remove ferns until the end of the growing season.

Boron deficiency may cause deformed fruit or uneven bud break. A foliar spray of 1.5 lb/100 gal water/acre of Solubor may alleviate these symptoms. Excess B may be toxic, so apply soil or foliar B with care and only when need is indicated by soil or tissue test.

POSTED 5/30/03

Blueberries have become a popular crop in the home garden. They require an acid soil, so will benefit from added peat moss at planting, and 2 oz. elemental sulfur sprinkled around each plant every two years. Pine bark mulch makes a good weed control. Fertilizing can be done with a foliar feed of a chelated iron product designed for acid-loving plants. There is a witch's broom condition showing up on blueberries. It is caused by an unusual fungus, and produces numerous swollen spongy shoots that have tiny leaves and no fruit. Fungicides are not effective, the diseased plants must be eradicated. Pruning out the brooms will not control it, as the whole plant is infected by the time it is noticed. The other host plant for this fungus is the fir tree (Abies). Do not plant blueberries within 1200 feet of fir trees.

Consider replacing part of the lown with groundcovers. Great suggestions for groundcovers in Vermont are in Leaflet OH55

Here's a short course in lawn care:
Spread a half inch of compost on the lawn every year. Scratch and reseed bare spots. Raise the mowing blade to 3 inch height. Leave clippings on the lawn unless they are too long or too wet and lying in piles. Fertilize once a year in the fall. Test the soil, add lime in the fall in amounts indicated by the soil test report to keep the pH optimal so nutrients are available to the grass plants. Let the grass go dormant during a drought, it will come back when the rains do. If you do all these things, your lawn will tolerate up to 12 grubs per square foot, will crowd out weeds, and will have a cooled root system that goes deep.

Pesticides aimed at grubs are not effective in April, May, and June. The grubs are too large, and the amount of chemical needed to kill them is much much more than if it were applied at the proper time. Apply grub control in late July through August in the Northeast. That is when the eggs are hatching and the larvae are small.

Milky spore needs grubs to maintain and spread the disease, so don't use chemical pesticides with it.

There is an organic product made with kaolin, a fine clay, that can be sprayed on plants to discourage the beetles from chewing on them. They find it incomfortable to walk on or bite into. The whole plant, however, is then covered with a white powder and it may need to be reapplied after a rain. Worth a try? Kind of ugly to look at.

The volcanoes are rising up around the trees and shrubbery again. Try to keep the mulch several inches away from the trunks of trees and shrubs so the bark can stay dry and impervious to insects and diseases. Keep the depth to 3-4 inches so the roots can breathe. Trees use shallow roots, studies have shown. Planting a tree at the proper depth and then burying it with mulch is inviting trouble, including accessory roots that grow into the mulch and then can girdle the tree, leaving it weakened for the next wind storm to topple it. Try for a bagel shape, not a volcano, when mulching trees.

Heads up for squash growers. Blossom end rot can be prevented by growing in well-drained soil, watering deeply during dry periods of weather, especially in the heat of summer, and mulching to maintain moisture. Avoid using a high ammonium fertilizer, which can burn the roots. It also locks up the calcium in the soil.

STRAWBERRIES mulched with red plastic have up to 90% more aromatic compounds than those mulched with black plastic. (From the "Avant Gardener", Vol. 32, No. 11, Sept. 2002).

POSTED 5/5/03

Dr. Pat Vittum, Turf Entomologist with the UMass Extension Turf Program, has developed a list of possible sources of entomopathogenic nematodes for white grub control. To read the complete message, please visit:

The UMass Extension Turf Program:

UMass Extension's Landscape, Nursery and Urban Forestry Program:

POSTED 4/8/03

TIMING IS EVERYTHING! Several common problems that show up later in the summer can be prevented by proper timing of treatment, which means at budbreak in the spring.

APPLE SCAB is a fungus disease spread by spores which are especially active during warm spring weather with high humidity. It causes defoliation, reduced yields and blemished fruit. All apples are attacked, including ornamental crabapples. Control is possible through planting of resistant varieties, sanitation and/or fungicide application. Resistant varieties include Jonafree, Macfree, Liberty, Freedom and Nova Easy-gro. If you insist upon growing McIntosh, Red Delicious, Roma, or Cortland, be prepared to follow a strict fungicide spray schedule. The most crucial time for spraying is from the time the green tips of the first leaves appear until the fruit is set, usually from beginning of May to mid-June. Spray application should be every 7 days during that period. Remember, fungicides work by providing a protective coating to block out spores, not by killing spores. So sanitation, fall clean-up, etc., is also needed. Also keep trees healthy by watering, fertilizing, and proper pruning. This information and more is available on the Leaflet GD17, which can be obtained by calling the Helpline.

VIBURNUM: If your viburnum has twisted, curled, distorted and cupped foliage, it may be from the SNOWBALL APHID. If so, add this shrub to your list of plants to be sprayed with dormant oil. The eggs are on the twigs and buds and hatch along with the first buds opening in the spring. If you are planning to plant viburnum, choose the resistant 'Viburnum tomentosum'. See leaflet EL176.

EUONYMUS CATERPILLAR: The larvae hatched last summer and waited all winter under their eggshells for the spring to begin feeding within a small web which expands as the colony grows. Break this web open with a stick and let the birds feast on the larvae. If you have no birds, Bt or other organic insecticides for defoliators will help, but break open the webbing first. See leaflet EL256.

POSTED 3/17/03

There are some leaflets available to assist you to get ready for the gardening season. GL's (Garden Leaflets) discussing timely subjects for the upcoming busy season can be requested from the Master Gardener Program by calling the Helpline at 1-800-639-2230 or (802)656-5421 and leaving a voice-mail with your request, your name and mailing address, and any other questions you may have.

OH14 FORCING FLOWERING BRANCHES ( and provides a handy chart of plant type, bloom color, when to cut and weeks to force. Directions for successful forcing are also included.

GL9 COLD FRAMES/HOTBEDS includes schematic drawings for construction of frames.

GL13 FROST PROTECTION for those who can't wait until last frost to get something set out. Suggests which crops are best to start early, and various products to use as cover against frost.

GL28 USING DORMANT SPRAYS TO CONTROL OVER-WINTERING PLANT PESTS stresses the importance of timing when applying dormant sprays, which is" before new growth begins in the spring or green tissue is visible, but after buds start to swell". Consider dormant lime-sulfur spray if you have probelems with aphids, mites and scale insects. Also used to control powdery mildew, rust and black spot on dormant roses. Raspberry and blueberry cane blights can be reduced by lime-sulfur applied jus before buds begin to break in the spring.

GL37 CONTROLLING TRANSPLANT HEIGHT has some non-chemical tips on keeping those seedlings short and stocky.

USDA BULLETIN: HOW TO BUY LAWN SEED lists the most frequently used grass seeds, explains their characteristics and what to look for on the label.

Just a mention of SNOW FLEAS, which may show up before this winter is finished. They usually appear as "thousands of little black things jumping around in my front yard". They are not fleas at all, but primitive insects named Collembola, commonly called springtails. Snow fleas ARE HARMELESS and actually help break down leaf litter, etc., on the soil. They will not bother people or pets, and will not get into the house, or contaminate foodstuff.

Think about ordering SOIL TEST KITS (see phone numbers above) before things get really busy.

POSTED 1/29/03

There are several leaflets of information available for helping to deal with problems that can show up on houseplants at this time of year.

Lists insects that attack plants mostly by chewing and sucking, such as aphids, mealybugs, and scale. Also spider mites. Controls discussed include prevention as well as non-chemical means of removal.

Discusses fungus gnats, tiny black flies that thrive in any plant grown in a high organic (i.e. peat-based) medium. They damage root systems as well as being a nuisance.

Provides a detailed and easy to read chart of symptoms and what the probable causes are. An example would be leaves that turn brown at the tips or margins are suffering from over or underwatering, too much or too little fertilizer, or low humidity (esp. in the house in winter). Also included is a brief listing of common insect pest problems on houseplants.

On the lighter side:

Here is all the information you need to be successful with seed-starting indoors.

Here is a listing of approximate dates for indoor seed-starting, using May 30 as the safe date outdoors for sensitive crops.

These last two leaflets are not available from the internet, but can be requested at no charge by calling the Master Gardener Helpline at 1-800-639-2230 or (802) 656-5421 any time and leaving a message with your name and address along with your request.

POSTED 1/6/03

Helpline staff found these two useful articles on the VERMONT ENTOMOLOGICAL SOCIETY website:

POSTED 11/14/02

WESTERN CONIFER SEED BUG has been turning up indoors lately to spend the winter.  They are smelly when squashed and can be a nuisance, but do not chew on anything nor do they present a poisonous problem. They can be vacuumed or swept up and disposed of. Spraying with a pesticide is only a last resort, and no one wants pesticides in the house. Prevention of this invasion of bugs (also applies to the ladybeetles and boxelder bugs) begins with making sure the house is well caulked around windows and doors and any other openings for pipes, vents, etc.

POSTED 10/17/02

BOXELDER BUG has been plaguing many homeowners by coming inside homes to spend the winter. They are smelly, especially when squashed, and a nuisance, but do not chew on anything nor do they present a poisonous problem. They can be vacuumed or swept up and disposed of. Spraying with a pesticide is only a last resort, and no one wants pesticides in the house. Prevention of this invasion of bugs (also applies to the ladybeetles) begins with making sure the house is well caulked around windows and doors and any other openings for pipes, vents, etc. Nearby boxelder trees may have to be eliminated. Maple trees are also a favorite host of these bugs.

PUTTING THE GARDEN TO BED for the winter is outlined on our factsheet number OH 03, 'Preparing the Garden for Winter'. Most important is clean-up of diseased plant material, disposing of it off-site.Do not put it into the compost pile unless you can maintain a very hot pile. An often forgotten but important cultural practice to prevent disease problems in the garden is the cleaning of tomato stakes and/or cages, trellises, tools, plastic supplies (row covers, hoops, jugs, etc.) with a solution of one part bleach to 9 parts water at fall clean-up to kill bacteria and fungi and not carry them over to the next season. APPLE SCAB fungus remains on fallen leaves and fruit and these should be cleaned out and disposed of to lessen the return of spores next spring.

BIRDSEED information excerpted from "The Avant Gardener", Vol. 34, No. 10 (Horticultural Data Processors, Box 489, New York, NY 10028) as follows: "Beware Birdseed: One of the most common components of bird feed is black oil sunflower seed. It is valued for its high-quality protein and as an oil source for avian diets.  Plant pathologists, however, have detected the overwintering form (sclerotia)of a plant-pathogenic fungus in some commercial sunflower seed. 'Sclerotinia sclerotiorum' can infect some 400 species of annuals, perennials, vegetables and woody plants. It causes a disease called cottony rot, which has been documented as being on the increase for the past several years. When birds discard infected seeds to the ground around the feeder, the sclerotia can lay dormant for months or even years, then produce spores that will infect plants. When plant pathologists at the Ohio Agricultural Research and Development Center (Wooster, OH 44691) tested ten bags of commercial sunflower seed, five were found to contain sclerotia of the fungus. Since there are no resistant sunflower varieties and no fungicides to control the disease, commercial growers are being urged to rotate their crops and monitor them for infection, and to practice double-screen cleaning plus gravity screening to reduce infected seeds to the lowest possible levels."

POSTED 9/19/02

LAWNS: Fall fertilization of lawns should have been accomplished by early September, but there is still time, right up to October, to apply limestone. To be most efficient, a soil test should be done. Soil test kits may be ordered from the Helpline at 1-800-639-2230 or 656-5421. The directions are all included, and payment is sent with the soil sample. The alternative is to follow the rule of thumb, which is to apply a nominal amount of lime if you haven't put any on in the last 3 years.

GREEN MANURE: Be careful when buying rye for green manure. There are 4 types of rye, and the one most often desired is ANNUAL RYEGRASS. This a small grass that can be planted up to 3 weeks before first frost, will be killed by the winter, and will leave a dead mat which can be turned into the soil in the spring and can be planted into immediately. PERENNIAL RYEGRASS will die back in the winter and then regrow in the spring, just like the lawn, which is where it is best used. WINTER RYE is a grain crop that grows 4-5 feet tall, dies back in the winter and then regrows in the spring. It can be tilled under when it is 10-12 inches high in the spring, but takes several weeks to decompose enough for planting any garden crops. It is also difficult to dig under by hand. SPRING RYE is a grain crop that is not common in the North.

POSTED 9/12/02

The Helpline has been receiving calls about Blossom End Rot on tomatoes. Here is the GD leaflet with information on it:

POSTED 8/20/02

Is it too late to use Merit to control grubs this year? Dr. Pat Vittum, Turf Entomologist with the UMass Extension Turf Program, has provided some tips on how to make the most of a Merit application.

POSTED 8/13/02

Hornets and Wasps
The Helpline is receiving requests for information regarding bee and wasp problems, which begin to become a problem now as the nests grow larger and the insects become more aggressive. The Entomology Leaflet EL31 is an excellent resource for information. Recent studies have shown that a 10% vinegar solution makes an effective weed killer, especially on young weeds. You can make your own 10% solution by buying household vinegar (a 5% solution) and boiling it down by half. Spray or wipe on with a sponge.

Wildflower Gardening
Anyone interested in starting a wildflower garden, meadow, patch, etc., should be getting the soil ready this fall. An informative and comprehensive article covering all the aspects of planting and maintaining a wildflower garden, "Planting a Wildflower Garden" written by Master Gardener Judy Lochbruner, can be found in the articles section of this website.

POSTED 8/02/02

Time Sensitive Advice: Grub Control Must Be Done Now
by Marge Westphal, Vermont Master Gardener

If you are treating for lawn grubs and if you are using imidicloprid (MERIT or BAYER SEASON-LONG GRUB CONTROL), it should be applied NOW, the first week of August. The window closes after that, because it must be applied before the grubs hatch.

"GRUB-EX" product used to include imidicloprid, but is now registered with halofenozide, which means it is effective on Japanese beetle only. If you have diazinon left and want to use it up, it should be applied after  eggs hatch, which is through August in the Northeast. This chemical is more effective if applied now, while larvae are small, rather than in the spring.

Milky spore disease is not effective north of Albany, New York.

For more details, refer to the "Grubs in the Lawn" section further down in the Seasonal Tips posted 5/10/02.

POSTED 7/18/02

Hydrogels, those sponge-like water retaining granules that are added to soil, may not be as safe as previously thought.  One researcher offers some concerns about their use.

POSTED 6/20/02

I've received several reports from northern Vermont of moderate to heavy defoliation of sugar maple by a small green looper called the Bruce Spanworm. Light numbers of the insect seem to be widespread and common. Caterpillars may also be found on beech leaves. A pest alert on the insect can be accessed at Please let us know of any moderate to heavy infestations.

Ronald S. Kelley
Forest Insect & Disease Specialist
Dept. of Forests, Parks and Recreation
29 Sunset Dr. Suite 1
Morrisville, VT 05661-8331
TEL 802-888-5733 FAX 802-888-2432

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POSTED 7/27/01: The weather patterns have brought warm temperatures with rains which means perfect disease conditions! Continue to look for:

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Last modified: July 02, 2003