acreage living October 1999

ISU cooperative extension

In this issue: acreage living home page

 Pasture Thistles

Carroll Olsenby Carroll Olsen, ISU Extension Field Specialist/Crops, SW Area Extension Center
Phone: 712-769-2600 - e-mail:

Weed life cycles are divided into four categories:
annuals, winter annuals, biennials, and perennials. Annuals are those that come up in the spring, seed in the summer, and die in the fall and include velvetleaf, buffalo bur, and foxtails. Winter annuals germinate and emerge in the fall, begin growing right away in the spring, and have usually flowered and died by June of the following year. Mustard species and downy brome are the most common examples. Musk thistle is the plant that comes to mind as a good example of a biennial weed. Perennials include Canada thistles, dandelions, milkweed, and other species that come back from the root each year.

Control measures usually include cultural, mechanical, chemical, and biological. Cultural control usually means having such a good stand that weeds don't get a chance. Mechanically, a mower and spade are still good options. There are a host of chemicals available to control thistles. Biological controls are also available for some weeds. Biological control is when we employ a live organism to control another live organism. For instance, there are thistle weevils that can help control the biennial thistle.

Now, for specifics. I'm going to emphasize biennial thistle and perennial weed control. Biennial thistles include those large purple flowered things in pastures and roadsides that start to bloom about July. Many counties include thistles on their noxious weed list, but they still persist. There are several different biennial species but they all die the same. Biennial thistles tend to germinate and grow to a "rosette" stage the first year then "bolt" or grow tall and flower the second year. They are tough to kill with chemicals after they bolt. There will always be a very few that act as annuals -- germinate and bloom in the same year.

Persistent use of a spade will do a good job of controlling biennial thistles as well as providing exercise if thistle numbers are limited and the surrounding growth is not so tall as to hide the offending plants.

Thistle weevils were actively introduced in the western half of Iowa during the early 1 980s in hopes of establishing a sustainable population of weevils in the state. According to an ISU publication, "Musk Thistle," IPM-45 (available at your county ISU Extension office) only about one-third of the seeded counties were considered to have an established colony of musk thistle weevils. And, we may have expected too much from the weevils --there were just too many thistles. In that case, they can be helped by using chemical control in the fall. Spraying in the spring might hurt weevils by killing their food source for the summer. Keep in mind that perfect thistle control will also eliminate weevil habitat. But it would be hard for me to believe we'll ever reach that state of control.

All perennial and biennial weeds die easier in the fall than in the spring because they are moving food to the roots in preparation for winter and the chemical just tags along. In the spring, food is coming from the roots and chemical translocation is almost nil.

I'd like to control these weeds with cultural methods, but they are formidable foes. Canada thistles have an extensive underground root system and tillage just tends to spread the weeds by cutting the root and replanting them. Persistent mowing so as not to allow plants to seed or replenish the root system with food would have a better chance, assuming you can get to all of them with a mower.

Now for chemical control, the method most of us ask about first. I've saved this for last because I'm making several assumptions about the area in question: 1) we're talking about a grass pasture -- no legumes because whatever chemicals we use to kill thistles will also kill broad4eaved forages, and 2) whatever chemicals we use on Canada thistles will also kill biennial thistles and most other broad- leaved weeds. However, biennial thistles die easier and can be controlled with lesser rates than Canada thistle. As usual, read and follow the label. Persistence is also key for chemical control of Canada thistle. Seems like we can kill the tops fairly easily but the plants come back from underground buds.

One of my counterparts in East Central Iowa, Jim Fawcett, has done several plots during the last couple years with treatments made on October 8, 1998, May 19, 1999, and late spring, June 8, 1999, on the same plots. In general, anything Jim used with Tordon had a better rating. Adding Banvel increased the cost per acre; adding 2,4-D reduced the cost per acre compared to straight Tordon. (Tordon is a restricted use pesticide so must be applied by a certified applicator.) Stinger was a close second for control but a more costly application. I've had a plot in Page County for a couple of years using chemicals at lower rates than Jim used and have yet to be successful in controlling Canada thistles. For a copy of Jim's Canada thistle plot results, contact either me or Jim. Another counterpart of mine, Mike White, has written publications on both musk thistle control and Canada thistle control that includes excellent discussions concerning both weeds. The pamphlets also give suggested product rates to control biennial thistles and Canada thistles. You can get copies of either or both pamphlets by contacting Mike or your county ISU Extension office.

For those of you on the web, you might want to check an article on the efficacy of 2,4-D and fall spraying at by ISU weed specialist Bob Hartzler. The time for effective fall spraying, how ever, is nearly over. Another source of information from ISU Extension offices is WC-92, "Herbicide Guide for Professionals," an ISU publication.


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 Small Farm Digest Available

Small Farm Digest is published quarterly by the Cooperate State Research, Education, and Extension Service to help small U.S. farms survive and thrive.

Subscriptions to Small Farm Digest are available to the public at no charge. Contact LaTracey Lewis, Small Farm Program, Plant and Animal Production, Protection, and Processing, U.S. Department of Agriculture, Mall Stop 2220, 1400 Independence Avenue, SW., Washington, DC 20250-2220 (telephone: 202-401-4587 or 1-800-583-3071; fax: 202-401-1602; e-mail: Visit the Small Farm Program web site (including a web version of Small Farm Digest) at


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 Deer in Winter Landscapes

Eldon Everhartby Eldon Everhart, ISU Extension Field Specialist/Horticulture, Shelby County
Phone: 712-755-3104 - e-mail:

In most of Iowa, hunting does not keep deer numbers In balance with the natural food supply. During the winter, deer survive by eating trees and shrubs. Reports by the Iowa DNR indicate that browsing damage by white-tailed deer continues to cause extensive damage to forest and Christmas tree plantations and natural regeneration of trees across the state. In addition, increasing amounts of damage to landscape plantings are occurring in the urban/rural interface.

Favorite winter food of deer includes evergreens, such as Douglas firs, yews, arborvitae, and junipers; and deciduous plants, like dogwoods, birch, apple, and flowering crabs.

In late winter, if deer populations are large and more palatable food is scarce or covered by deep snow, deer will eat almost any plant.

deerVery hungry deer will eat thorny plants, such as barberry, buckthorn, red cedar, and Russian olive, as well as bad tasting plants like honey- suckle, balsam firs, potentilla, lilac, and spirea.

What can you do to protect your orchard and landscape plantings from hungry deer? An eight foot tall fence is about the only sure way to exclude deer. Unfortunately, a tall fence encircling your property is expensive and unsightly.

A cheaper but less effective tactic is to enclose plants with snow fence. Deer usually avoid small, penned-in areas. Covering lower branches with netting is of little benefit.

You could also try repellents. These include putrescence whole egg solids (Big Game Repellent and Deer Away), ammonium soap of fatty acids (Hinder), bone tar oil (Magic Circle Deer Repellent), and thiram fungicide.

Deer-Off is reputed to last twice as long as most repellents because rain or snow will not wash it off. It is available in a ready to use spray or a concentrate. (For more information call 1-800-333-7633).

Aromatic soap bars (with wrappers left on) or human haiir, blood meal, or tankage from animal rendering (in perforated plastic bags or nylon hosiery) may work when hung on limbs.

All these products either taste bad, smell nasty, or are associated with humans. They discourage deer when applied directly to plants. Most of them must be reapplied when rain and snow takes its toll.

Unfortunately, repellents are usually only partially effective, especially if deer have fed on the plants before repellents were applied. In addition, most deer learn to ignore repellents.

A recent study at Cornell University shows that free-ranging dogs contained within "Off-Limits Crop Protection Systems" severely reduces deer damage.

The OffLimits system works by using dogs to scare the deer out of the orchard. A dog is fitted with an electronic shock collar and enclosed in an area by a buried wire that activates the collar when the dog nears the wire. The collar beeps when the dog gets within 30 feet of the wire and gives a shock if the dog is next to the wire. This allows the dog to chase deer away from the protected area without running after the deer once it leaves the area.

Newly planted orchards also benefited from the OffLimits system according to the study. After two seasons of growth, dog-protected trees had nearly three times the canopy cross-sectional area of the control trees.

Special deer control permits can be obtained for farms, orchards, tree farms, nurseries, and Christmas tree farms where damage by white-tailed deer is a problem.

Since the 1997 session of the Iowa Legislature, the Department of Natural Resources (DNR) has two types of permits available to control excessive deer populations. One permit allows harvest of extra animals during hunting season. The other type allows deer to be taken after the hunting season.

Contact the DNR biologist in your area and get a record in writing of all damage. If your damage is $1,500 or more, you are eligible for the permits.

To report damage, call your local DNR office or Don Cummings, DNR state office, 515-281-5529.

For additional information on identifying and controlling deer damage, ask for ISU Extension publication, "Managing Iowa Wildlife: White-tailed Deer" Pm- 1302g), available for $1.50 from your local county ISU Extension office and from Extension Distribution, 119 Printing and Publications Building, Iowa State University, Ames, IA 50011, phone: 515-294-5247. A web version can be viewed at: PM1302G.pdf (pdf-format).


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 For Wildlife, Use WHIP

Shawn Shouseby Shawn Shouse, ISU Extension Field Specialist/Ag Engineering, SW Area Extension Center
Phone: 712-769-2600 - e-mail:

The USDA Wildlife Habit Incentives Program (WHIP) was established by the 1996 Farm Bill. WHIP is designed to help farmers, ranchers, and other landowners protect important wildlife habitat. Participants prepare and implement a wildlife habitat development plan with assistance from USDA's Natural Resources Conservation Service (NRCS) and their local conservation districts. Eligible areas include native grasslands, savannas, barrens, certain types of forest land, riparian forests, and aquatic habitat such as rivers, streams and adjacent stream banks, wetlands, and uplands as well as other areas.

WHIP provides cost-share assistance for up to 75 percent of the cost of instituting wildlife habitat practices. Cost-share payments of up to $10,000 are available for each WHIP agreement, which is in effect for a 5 to 1 0-year period.

For additional information, contact your local USDA Service Center or state NRCS office, or visit the NRCS home page ( select "Farm Bill.") Questions may be directed to Jeanne Christie, National Program Leader, WHIP (telephone: 202/720-3534; fax: 202/720-2143; e-mail:

This article is reprinted from the winter 1998 issue of Small Farm Digest. Small Farm Digest is published quarterly by the Cooperative State Research, Education, and Extension Service, United States Department of Agriculture, Washington, D.C. 20250-2220. Click here for the previous article with subscription information.


Acreage Living is published monthly. For more information, contact your local county ISU Extension Office.
Editor: Shawn Shouse, ISU Extension FS/Ag Engineering, SW Area Extension, 53020 Hitchcock Avenue, Lewis, Iowa, 51544, Ph: 712/769-2600
Layout & Design: Paulette Cambridge, Office Assistant, SW Area Extension, 53020 Hitchcock Avenue, Lewis, Iowa 51544, Ph: 712/769-2600

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