Spring finally arrives in South Dakota

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By David Graper

SDSU Extension Horticulture Specialist

The spring of 2018 was punctuated with several false starts and a few major setbacks. But, now it appears that spring is here to stay, and some gardeners have already experienced a taste of early summer weather. Of course, this is nothing new for South Dakota. Our weather is notoriously difficult to forecast, and it can certainly change very rapidly.

While some gardeners might have been alarmed by the chilly weather and snow that many areas received over the last few weeks, it likely caused little damage to our perennial flowers and vegetables, shrubs and trees. Had we had significantly warmer temperatures earlier this spring that would have stimulated many plants to come out of dormancy and begin growth, plants would have been damaged much more by the cold temperatures. Snow, while more dramatic, is actually a great insulator for our perennials as it helps to keep the ground cooler, slowing growth and also holding in the warmth of the soil to protect developing new shoots. Plus, it gives us the added bonus of additional moisture. While some gardeners might feel we have plenty of moisture as some gardens still have standing water, folks out West River are generally happy to get whatever moisture they can get at this time of year.

So, did the snow and below average temperatures cause any damage to our perennial flowers and vegetables and lawns? For the most part no, other than to delay their development. And, of course it has delayed gardening activities because it was simply too wet to get out and do very much. Last year on April 27, most of our spring flowering bulbs at McCrory Gardens were coming into bloom, with the Narcissus in full bloom. But, we also got some pretty cold weather the night before that froze up our fountain in the Perennial Garden. This April 27th, the spring bulbs are just showing good growth but have no signs of flower buds yet. By May 5, our tulips in the TuliPalooza beds at McCrory were in full bloom. However, the warmer temperatures and wind have been quickly drying out gardens and yards, so plants should start catching up quickly. But, I still doubt that we will have many tulips in bloom by May 5 this year. That means that our display of over 8,500 tulips for TuliPalooza this year will just start a little bit later and will be more likely to still be in their full glory by Mother’s Day.

As the yard starts to dry out, it’s a good time to get busy with some spring cleanup. The snow, ice and wind likely broke off quite a few branches on trees and shrubs, so this is a good time to take care of those. If the soil is still fairly wet, you may want to dry to do as much of your yardwork on foot instead of risking compacting your lawn by running the garden tractor over it too much yet. Cut back ornamental grasses to about two inches above the soil line, particularly cool season grasses since those are likely already putting out new, green shoots. The old, dead shoots on your other perennials can also be cut down to about two inches. Be careful that you do not damage the tender new shoots that might already be emerging.

Asparagus should begin emerging soon too. So, if you have not already removed the remaining ferny stems from last summer’s growth, get those removed now so they won’t be in the way for harvesting the new tender spears as they grow up. Once the old shoots are pruned off and removed, I like to cover my asparagus bed with about two inches of good quality compost. This helps to provide nutrients to the asparagus and also will cover over any tiny weeds that might be already beginning to grow. If you don’t have access to compost, you can also purchase some inexpensive potting soil, and use that instead. You could also perform some shallow tillage over the asparagus at this time, since the new spears are still several inches below the soil surface. This can work well to get rid of winter annuals that might already getting some size to them, like Shepard’s purse or henbit. If you have perennial weeds like quackgrass, bromegrass or thistles, these can be sprayed with glyphosate now too, as long as there are no signs of the new shoots emerging yet and there is some growth of the weeds to allow for the uptake of the herbicide. Applying the compost around your rhubarb also works well to provide nutrients and retard weed seeds from germinating.

Raking the lawn is another spring ritual that many gardeners perform, and some even like doing it! Personally, I do not like raking and do as little of it as I can. But it is a great way to clean up the lawn, get rid of some of the old, dead grass and leaves and make the lawn look nicer as it begins to green up. If you did not fertilize your lawn last fall, the first couple weeks in May are a great time to put on some lawn fertilizer, applying about one pound of actual nitrogen per 1,000 square feet, as described on the fertilizer bag. Remember it is a good idea to put it on at half rate and apply it in two different directions to avoid any stripes where you might not have overlapped enough. Broadcast spreaders work better than do the drop-type spreaders, especially for larger lawn areas.

If you had a broadleaf weed problem in your lawn last year, hopefully you treated it last fall, which is the best time to treat the weeds. Many gardeners wait until spring, when they see those yellow dandelion flowers to try to treat them. Spring applications can certainly stunt dandelions and other weeds, but it is less likely to kill them, compared to fall applications. We also have to be concerned with trees, shrubs and perennials that are just beginning growth on our landscapes. They are very susceptible to damage from these broadleaf herbicides, so be very careful. Only treat when the wind is calm and if possible, just spot spray weeds instead of spraying the entire lawn.

Wood plant care for early May 2018

By John Ball

SDSU Extension Forestry Specialist

Finally, we are beginning to get some warm weather, but we are about a month behind our typical plant development. This Tuesday the cornelian cherry (Cornus mas) was just beginning to bloom in Spearfish, usually that occurs in late March.

How have evergreens performed in this long winter weather?

Reports of desiccation injury on arborvitaes, junipers, and yews are beginning to come in from the southern part of the state. The combination of a dry fall and a long winter has left many of these plants susceptible to desiccation injury. This injury appears as yellow to browning foliage that will turn red in the next few weeks as our temperatures continue (finally) to warm.

The only treatment is to begin watering these evergreens as soon as the ground can absorb moisture (now in many areas of the state) and prune off any branches as they die. I would delay the pruning until it is obvious that the branch has died. Some lightly discolored branches may recover, however “once red, it’s dead” and should be pruned off. We may also see an increase in phomopsis injury on arborvitaes and junipers due to this twig injury. The disease can be managed with an application of a copper fungicide applied as the new growth begins expanding this spring and then repeated for about three times, 10 to 14 days apart.

We may also see an increase in desiccation injury on young evergreen plantings in windbreaks. Spruce are also vulnerable to winter desiccation injury, and even pines to a lesser extent, and expect to see some of the same symptoms on young trees planted this last spring – yellowing to reddening foliage. Now is the time to check the buds on the tips of seedling branches and twigs exhibiting discolored foliage. If the buds are dry and discolored the shoot will not expand and the branch or even the entire seedling may be dead. I also expect to see desiccation injury on blue spruce, regardless of age, it is not a very tolerant tree of this type of injury.

Black knot (Apiosporina morbosa) is a fungal disease that is common on chokecherry trees. You can occasionally find it on plums here though — it is a major problem in plum orchards in other states.

The name black knot comes from the most noticeable sign of the disease, a cylindrical mass of black, woody knots along shoots. The knots will eventually girdle the shoot and kill the tips. If a knot forms on the stem, it can kill the entire tree.

Many people mistakenly believe if they prune out the knots they eliminated the disease, only to be disappointed when it reappears several month later. The knots form the second year of infection. The first-year infection is only a slight swelling along a shoot that is perhaps a little lighter in color than the surrounding shoots.

If a gardener has time and patience, they can go out now and prune out all the knots and swollen shoots to eliminate the disease. The pruning should be done at least six inches below the visible infection and all the infected clippings burned.

The best management is basal pruning, remove the infected tree. Once infected, a tree will just become infected again. Some trees are more susceptible to this disease than others and some trees never get the disease.

Fungicides may also be used for management of the disease. Fungicides containing chlorothalonil as the active ingredient and labelled for black knot may be used. The first application is made as the buds begin to swell (usually when we start getting temperatures above 60°F) and repeated every seven to 10 days until shoot expansion is completed in June. Chlorothalonil cannot be used after bloom if the fruit will be harvested for human consumption.

“Ready, Set, Grow!” rescheduled

The Coteau Prairie Master Gardeners’ 4th annual free seminar “Ready, Set, Grow!” has been postponed from April 14, to May 5, at the Codington County Expo Building (1910 W. Kemp Ave.) in Watertown. Speakers have been rescheduled. Members are hoping those planning to come on April 14 will be able to attend on May 5, when the weather is hopefully better! The theme “Right Plant, Right Place” will be featured. The event will be in the North Expo; use west entrance off 21st St. W., Entrance H. Registration and refreshments begin at 8:30, speakers begin at 9:00 and end at 2:00. A catered box lunch is available for $10 and can be ordered at registration. An afternoon ‘make and take’ session is available for $7, where participants can make their own hypertufa pots from newspapers, ending the day at 2:00 p.m. Preregistration is not required.

Topics and speakers include: Unique Plants and Veggies – Vikki Schaack, Medary Acres, Brookings; The Best Plants Tested at McCrory Gardens During 2016 and 2017 – Dr. David Graper, SDSU Extension horticulture specialist; Great Container Plants & More! – Lori Seim, Sioux Valley Greenhouses, Watertown. The afternoon session is Make Your Own Tufa Pot from Newspapers – instructors Deb Cass and Lori Seim.

Join us to learn more about putting the right plant in the right place! For more information, contact Dianne Rider, president, at 881-3975, or visit and ‘like’ their Facebook page:

Sign up for 2018 Master Gardener Training

SDSU Extension Master Gardener Training is provided by SDSU faculty and includes access to online training materials, a resource manual, and hands-on classes. Hands-on classes will be held in three locations, over eight sessions. Each session begins at 8:30 a.m. and ends at 4:30 p.m. local time. Come join the fun!

When/Where: Participants can select one of three training locations:

• Huron – Fine Arts Building, 939 Ohio Ave SW : June 5, 12, 19, 26, July 10, 17, 24, 31.

• Pierre – Regional Extension Center: June 6, 13, 20, 27, July 11, 18, 25, Aug 1.

• Rapid City – Regional Extension Center: June 7, 14, 21, 28, July 12, 19, 26, Aug 2.

Topics Include: Basic botany and taxonomy; soils and fertilizers; turf and weed management; plant pathology/composting; tree and shrub care; pest management; planting and landscape use; pesticides; insects and pollinators, biodiversity; vegetables and season extension; herbaceous ornamentals, native plants, plant propagation and more!

Cost: There are two training options:

• Training with Volunteer Commitment as an SDSU Extension Master Gardener – $250.

To take course at discounted rate, you must provide 50 hours of volunteer service over the next two years as a Master Gardener. The balance of the full course fee will be invoiced if service commitment is not completed. Obtain 6 CEUs.

• Training to Obtain Certificate of Recognition in Horticulture – No volunteerism required – $600.

Participants will receive the same training but will not be required to volunteer and will receive a Certificate of Recognition in Horticulture. Obtain 6 CEUs.

Register today at Having trouble registering? Contact us at or call 605-782-3290. Registration deadline is May 19.

Perennial Garden fountain in ice. iGrow photo
Black knot disease. iGrow photo
Cornelian cherry in bloom. iGrow photo
Cut back ornamental grasses before they begin growth in the spring. iGrow photo
TuliPalooza bed. iGrow photo
Narcissus bulbs emerging. iGrow photo