Yard & Garden Line News Volume 7 Number 14                                                               September 1, 2005

Features this issue: Fall is the Time for Planting Garlic White Grubs During Late Summer Northern Corn Rootworms in Home Gardens Weed ID 101--Virginia Copperleaf September Garden Calendar Editorial Notes

Fall is the Time for Planting Garlic
Carl Rosen

Hardneck garlic. Photo credit: Carl Rosen

If you want fresh garlic to harvest from your garden next summer, the best time to plant is in the fall. Garlic can also be planted in early spring, but the bulbs are usually smaller compared with fall planting and if planted too late in the spring, bulbs may not even form. The reason is that garlic needs a cold treatment to initiate the bulbing process.

In general, garlic in Minnesota should be planted within one to two weeks after the first killing frost (32 degrees Fahrenheit). In northern Minnesota, planting during the third to fourth week of September is recommended, while in southern Minnesota planting around the first or second week of October is recommended.

There are two general types of garlic that can be planted: hardneck garlic or those that produce a flowering stalk, and softneck garlic or those that do not produce a flowering stalk. The hardnecks are the recommended types for cold climates because they are generally more winter hardy than the softnecks.

Garlic does not produce true seed and therefore individual cloves from a bulb are used to propagate new plants. Bulbs can be purchased from various mail order seed companies or local garlic growers. Do not use bulbs from the grocery store because these types of garlic are usually not well adapted to Minnesota conditions.

Some hardneck varieties that grow well in Minnesota include: Music, Northern White, Chesnok Red, German Red, and Spanish Roja. A few softneck varieties that perform well in most years are: Inchellium Red, New York White, and Polish Softneck. You can also experiment with other varieties to see if they perform well in your area. The amount of garlic bulbs to purchase depends on the variety. One pound of garlic bulbs can contain anywhere from 20 to 80 cloves.

Weeding. Photo credit:  Carl Rosen

Garlic grows best in a well-drained soil high in organic matter. Add compost to your soil before planting and incorporate well. To plant, gently break the cloves from the bulb and place the clove in the ground with the pointed tip up. Planting depth should be about two to three inches below the soil surface and space cloves about 4 inches apart in the row. The cloves can be planted in beds with multiple rows. After planting, the rows should be covered with three to four inches of leaf or straw mulch. This will protect the plants from frost heaving and will also provide some weed control the following spring.

Let the plants emerge through the mulch the following spring. Keep weeds under control and water periodically if the soil becomes dry. Hardneck garlic will start to flower in mid to late June. For maximum bulb size, cut the flower stalks (often called scapes) off about 7 to 10 days after they emerge. The flower stalks are considered a delicacy by many and can be chopped and then cooked by steaming (like green beans) or used in a stir fry dish.

Garlic is ready to harvest when about half the leaves turn brown. This normally occurs in early to mid-July for southern Minnesota and late July to early August in Northern Minnesota. Dig the plants with a pitch fork. Remove as much soil as possible by gently shaking the plants. Bunch about 10 plants together with twine and hang in a cool dry place for about three to four weeks. Once the shoots and roots have dried down, the tops should then be cut about one inch above the main bulb and roots should be trimmed close to the base of the bulb. Garlic can be stored for several months in open containers in a cool dry location. Some of the bulbs can be used for planting a crop in the fall for harvest the following year.

For more information on growing garlic in Minnesota refer to the following website:
http://www.extension.umn.edu/distribution/cropsystems/DC7317.html

White Grubs During Late Summer
Jeffrey Hahn, Assist. Extension Entomologist

White grub Photo credit: Jeff Hahn

There have been a number of people that have recently discovered white grubs, Phyllophaga spp., in their lawns. Sometimes people first became aware of this insect problem when they found racoons tearing into the lawn to get at the insects or in at least one case, birds (specifically robins) were pecking at the turf.

White grubs in Minnesota have a three year life cycle. In the first year, adult June beetles lay eggs in the soil during early summer. The immature larvae feed a little and grow no larger than 1/2 inch long. Damage is not detectable then. During the second year of development, white grubs range up to 3/4 inch long. Dead patches of grass may be seen but more times than not the damage is small enough that homeowners do not see it.

Finally during the third year of their life cycle, white grubs reach their full grown size of one inch long. Damage becomes much more conspicuous. This is the stage that people are finding now. Yet, it is not unusual for people to miss symptoms of white grub earlier in the season and first realize there is a problem during mid to late summer. Sometimes they mistakenly believed the brown grass was due to drought or some other cause.

Are there any options for this year? Not really. Unfortunately, white grub feeding is almost finished and they have inflicted basically as much damage as they are going to do for the year. They will pupate either this fall or early spring next year to develop into adults. Even for people who found this insect problem in late July or early August, it would have been difficult to quickly kill the grubs as most of the insecticides available are slow acting.

So what should you do next year? The odds are that next spring there won't be any white grubs in your turf. Because you had a problem this year does not automatically mean that they will return to your lawn and lay eggs in 2006. Ask yourself how often you have had a white grub problem in your turf. If you do no encounter them very frequently, then the odds of another white grub infestation will be in your favor.

Still, it is possible that not all of the larvae were third year grubs this year and there may be additional feeding next season. Inspect your lawn next spring in case you still have an active infestation. If you find turf that pulls up easily, i.e. the roots have been chewed, that is evidence of white grub feeding.

If you have had more frequent problems with white grubs, don't expect problems next year, but monitor your lawn closely in 2007 and early 2008 when damage is first likely to be seen. Also keep in mind that white grubs are not strictly synchronous and a white grub infestation can show up in a lawn any given year.

If you can detect white grubs early in the season, treat them as soon as possible to minimize their damage. You can treat them with one of several insecticides labeled for grubs: Imidacloprid (e.g. Scott's® GrubEx® Season-Long Control), Halofenazide (e.g. Hi-Yield Kill-A-Grub and Spectracide® Grub StopTM Once and DoneTM), and Dylox (trichlorfon) (e.g. Hi-Yield 6.2 Granular).

Imidicloprid and halofenazide are slow acting and are not meant to be used as a quick solution for white grubs. For example, imidicloprid can take up to 34 days to kill grubs. Dylox is quicker acting but may be harder to find in stores. Be sure treated areas are watered thoroughly after application to help move the insecticide into the root zone where the white grubs are located.

Northern Corn Rootworms in Home Gardens
Jeffrey Hahn, Assist. Extension Entomologist

Northern corn rootworm on rose. Photo credit:  Jeff Hahn

A northern corn rootworm, Diabrotica barberi, is a small insect, about 3/16th inch long. It is a pale, uniform green, lacking any type of markings (e.g. spots or stripes). It is common in Minnesota and throughout the Midwest wherever corn is grown. This summer, northern corn rootworms have been particularly numerous probably due to favorable weather conditions.

This beetle typically has a one year life cycle, although there is evidence that it can be extended to two years. Northern corn rootworms overwinter as eggs. These eggs are laid in the soil at the base of corn plants. They hatch the following June and the larvae start to feed on corn roots. The larvae are active for four to six weeks before pupating. They emerge as adults in July, about five to ten days after they pupate. After feeding they lay eggs, generally during August and September.

Adults typically feed on the silk of corn plants. However, they can also feed on the blossoms of a variety of flowers and can have an impact in nearby gardens. They chew ragged holes and can make blossoms unsightly. The severity can range from slight to heavy.

If you encounter a problem with northern corn rootworms, you have several options. You can ignore them especially if they are not very abundant. You could also physically remove them by shaking plants so the beetles fall into a pail of soapy of water. If they are numerous and you wish to preserve your flowers, you can easily manage them with an application of a garden insecticide, such as permethrin, esfenvalerate, or carbaryl.

Get the low down on this month's insect pests at Insects http://www.extension.umn.edu/projects/yardandgarden/EntWeb/Ent.htm

Weed ID 101--Virginia Copperleaf
Beth Jarvis, weed grower

Virginia copperleaf Photo credits: Beth Jarvis

On a recent visit, a friend pointed to some weeds in my back yard and asked "What's that? I have it all over!"

So I seized the opportunity to introduce her to Virginia copperleaf (Acalypha virginica) also known as three-seeded mercury, copper-leaf, mercury-weed or wax balls. My favorite weed book says it ranges west to South Dakota and Texas.

It's a member of the spurge family and typically associated with fields, stream beds, horticultural and agricultural crops.

My friend's question didn't surprise me as Virginia copperleaf has become more prevalent in my yard over recent years. Yet, Roger Becker, Extension weed scientist, says he's not noted any population increase over the last 10 years or so. At the moment it's one of the 10 most common in my yard though it's not made anyone else's top 10 list that I know of. So, I guess when you have a talent for raising something, go with it.

This annual is spread by seeds and has a shallow root system, so it's easy to pull. When it germinates in late spring, it doesn't discriminate between sun or shade though young plants in sunnier sites will acquire a coppery tint to their leaves. It can reach a mature height of three feet and has "erect, branched stems".

The flowers are inconspicuous, forming in clusters in the leaf axils, where the leaves attach to the stem. Flowers are either male or female flowers but both are found on the same plant, making it monoecious.

Control? The most organic method is to pull it. Pre-emergents for broadleaf weeds work in spring as would post-emergence herbicides for dandelions and similar weeds. Of course, you need to read the label of any herbicide you use and follow the directions exactly.

September Garden Calendar
Compiled from conversations with Bob Mugaas, Patrick Weicherding, Regional Extension Educators

Helianthus sp. Photo credit: Beth Jarvis

Trees and Shrubs:

Water, water, water. Trees and shrubs planting with the last five years should receive 1- 1.5" of water per week.

Refresh mulch and replenish to bring level up to 3-4" over root zone. Mulching preserves soil moisture plus may provide insulation against early winter cold in years where snowfall is scant. Deep penetrating freezes can injure roots and impare next summer's water and nutrient uptake.

Be very careful about fall broadleaf weed control, particularly those that contain dicamba (such as Trimec, 3-Way) as you can still get uptake through the roots.

Lawns:

Even though the summer gardening season is winding down, the lawn growing season is by no way over. We are entering the fall growth period for the turfgrass community which is a very active time. We need to think in terms of "grass gardening" and apply the same good garden practices to our lawns that we do to our other landscape plants.

All perennial plants need to prepare physiologically for winter. To accomplish the winter shut down functions, they must not be under stress, especially lacking water. If they are drought-stressed, they can't acclimate for winter and may be injured or killed by winter. So keep watering your lawn.

The first weekend in September is a great time to apply the first of two fall fertilizer applications. You can use a regular fertilizer; winterizer fertilizer is not necessary. You can use weed and feed if you have lots of weeds. It is better, though, to separate fertilization from weed control and treat the broadleaves weeds in mid to late September.

The next couple of weeks are prime time to seed, or re-seed a lawn. It's also still a great time to lay sod. Power raking/vertical mowing to a depth of 1/2 inch could be sufficient for reseeding a thin lawn. Tilling to a depth of 6 inches or so is recommended when incorporating fertilizer, soil amendments or following soil compacting-construction. Be sure to keep newly planted areas watered although shorter days and cooler temperatures create less of a water demand.

You may not need to mow as frequently but you should continue to mow. As the leaves begin to fall, you can mulch a light layer of leaves into the lawn. The lawn will looked raked as the mulching mower will cut the leaves into small pieces. If the leaves pile up thickly, re-distribute them. You should not see windrows of chopped leaves.

Fruits, Flowers and Veggies
Blossom end rot has show up on a lot of tomatoes. Tomatoes develop a dark patch on the bottom/blossom end. This results from a lack of calcium but it is brought about by uneven watering. It is common in drought-stressed tomatoes and ends once the tomatoes receive regular waterings.

I've also seen sunscald on tomatoes in my garden. They have yellow "shoulders" that covers hard, white tissue. It could be somewhat cultivar-dependent as I have it only on one of four cultivars.

Fall-bearing raspberries should be ripening soon. If you only want the fall crop, cut them down after they produce, otherwise, they'll produce fruit next summer. Then you can certainly cut them down.

Apples are ripe when the starches have converted to sugars. You can feel the starch on your teeth when you bite into an unripe apple. Just because it's red doesn't mean it's ripe.

Any diseased plant foliage should be destroyed and not composted. Most common plant dieases are caused by fungi so they will survive in a home compost pile as the compost does not heat enough to kill the mold spores.

Editorial Notes

Verbena and painted lady butterfly. Photo credits: Beth Jarvis

In the next issue, on September 15, Bob Mugaas will discuss the changing face of garden herbicides. The revised copy of the lawn care herbicides appeared in the July 1 issue. For October 1, Patrick Weicherding will write about on-going research at the U that's evaluating whether butterflying, scoring or teasing apart circling roots in container-grown trees makes a difference in the establishment of trees. With the October issue, we return to monthly publication, around the first of the month. For Nov. 1, Patrick will return with an article on killing trees. Buckthorn will be the only thing the woods with leaves so it will be easy to spot it and kill it.

Please feel free to cut and paste any of the articles for use in your own newsletters. All we ask is that you give our authors credit.

Back issues Yard & Garden Line News are on the Yard & Garden Line home page at www.extension.umn.edu/yardandgarden/.

Deb Brown answers gardening questions on Minnesota Public Radio's (MPR) "Midmorning" program on the first Friday of every month at 10 a.m. The program is broadcast on KNOW 91.1 FM, and available state-wide on the MPR news radio stations. (Scroll down for map.)

For plant and insect questions, visit http://www.extension.umn.edu/askmg. Thousands of questions have been answered, so try the search option in the black bar at the top left of the board for the fastest answer.

If you would like to receive an e-mail reminder when the next issue of the Yard & Garden Line News is posted to the web, just send an e-mail to: listserv@lists.umn.edu (note: the second E in listserve is omitted), leave the subject line blank, then in the body of the message, type: sub yglnewslist or to unsubscribe, enter: unsub yglnewslist

Happy gardening!

Beth Jarvis
Yard & Garden Line Project Coordinator


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