Category Archives: Plant Care & Plant Diseases

Tomatoes

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Coax Tomatoes & Peppers to Maturity
CORVALLIS, Ore. – There’s probably nothing more exasperating than working hard in the vegetable garden all summer, only to end up with hard green tomatoes, unripe melons, and sweet peppers the size of robin’s eggs.
Oregon ‘s cool springs and cool summer nights can prevent tomatoes and peppers from flowering and setting fruit early enough to grow to a decent size before the frosts of fall arrive.
Ross Penhallegon, horticulturist with the Oregon State University Extension Service, recommends using plastic sheeting to warm the soil. The sheeting comes in various colors including black, green and even red. Black seems to be the most popular color with vegetable gardeners.
“Lay sheets of black plastic on the soil where those heat-loving vegetables will be growing,” Penhallegon said. “The plastic absorbs heat during the day and keeps the soil warm during the night.”
Black polyethylene film in rolls three or four feet wide and 1 to 1.5 mils thick works fine, but Penhallegon recommends using thicker plastic if you want to use it for more than one season. If you want something that will decompose by the end of the year, look for black paper mulch.
Before planting peppers, melons and tomatoes, lay the plastic on the ground where the plants will grow. Cut six-inch holes in the plastic every two feet. If you use drip irrigation in your garden, put drip lines under the plastic.
If you use sprinklers to water, dampen the soil before you lay the plastic down and cut the holes larger to ensure that enough moisture enters the ground from the sprinklers.
Dig a hole for each transplant where there is a hole in the plastic. Then plant your plants. Be sure there’s enough plastic on all sides to cover a mature root system.
After everything’s planted, take a pitchfork and punch some holes in the plastic so water will soak through, but avoid the drip hose. Then weigh down the edges of the plastic with a few mounds of soil.
By Judy Scott, Oregon State University Extension Service
Source: Ross Penhallegon Oregon State University Horticulturist

May Horticulture Report: Peony Month!

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Peony report
By Gena Goddard
I think that May should be Peony month. The glorious peony is already known as the Memorial Day flower.  Why not celebrate it all month? My first peonies have already started blooming. The first to bloom is always the tenuifolia, fern leaf peony and probably one of the original flowers which was bred into the myriad of varieties we have today, the most common being the full double. The hybridizers of the 19th and 20th centuries started with average sized flowers with many yellow stamens and turned the stamens into staminoids which they were able to turn into petals. Sometimes science is a bit magical and hybridizers capitalized on that petal formation to make a huge fully petaled blossom sometimes 6” across.
                The next to bloom are the tree peonies (paeoniasuffruticosa).  I stuck two bushes together which bloom at the same time The first bush to bloom has dark magenta flowers, then a taller bush with large white flowers bloom above a week later. These blooms are large and the texture reminds me of crepe paper flowers made in Mexico. Then the yellow tree bush blooms.  It is an older bush at least 10 years old, but retains its small stature of only about 3 feet tall.
                After the tree peonies are done there is a little lull of about a week or two and then the herbaceous peonies (Paeonialactiflora)start.  I have the old standard, ‘festiva maxima’ white double with red flecks which blooms early and then my favorite pink Mrs. F.D.R.  It is so delicate with its longer petals. Then finally the reds like Karl Rosenfeld. By that time the month of May is over and so I fertilize with an all-purpose 5-5-5 and relax and let all my plants have a leisurely summer storing energy for next year.
When fall arrives the leaves turn a dark red and just before the first frost I cut them back to a couple of inches above ground so that I know where they are for next spring.  This fall I plan on digging up many of my plants and dividing them because the grass has invaded the whole bed and needs to be eradicated before I replant them back. When dividing dig up root, wash off most of the dirt so you can see the eyes for next year’s growth. Saw the root so that you have 3-5 eyes per root.  I am not looking forward to this task. When I replant I will make larger holes about 2’ diameter and in depth. I will also put lots of compost mixed with the native soil into the hole so that the eye is no deeper than 2” below the ground level.
                There isn’t a peony that I have seen that I don’t like.  I saw a native peony at Hyatt Lake and it’s little brown blossom was demurely hidden under the leaves.
Places I recommend for herbaceous peonies are Adelman’s Peonies in Salem, Oregon and Deason’s Peonies in Ashland, Oregon . For tree peonies, I recommend Brothers Herbs and Peonies in Wilsonville, Oregon.

Plant Resources:
Deason’s Peonies:     http://www.deasonpeonies.com/
Adelman’s Peonies:   http://peonyparadise.com/
Brothers Herbs and Peonies:  http://www.treony.com/

Garden Beet Newsletter

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Newsletter of the Jackson County Master Gardener™ Association
Read here: Garden Beet Newsletter-January 2012
Read here: Garden Beet Newsletter- February 2012

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A reminder- If your roses had blackspot last year now is the time to spray dormant plants with a mixture of sulfur and horticultural oil. The oil helps the sulfur cling to the canes during the rainy season, plus it kills overwintering pests. Spray only leafless canes. Repeat spray in the spring before new leaves appear.

Carlotta Lucas
Blog Editor

 

Blackspot on Roses

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Diplocarpon Rosae is a devastating fungal disease commonly known as backspot, and this year’s wet spring followed by the hot weather created perfect conditions for this disease to thrive on our roses.

Blackspot easily spreads from plant to plant by water droplets. The fungus starts on the bottom leaves in the spring and moves its way up the plant as the season progresses. If left unchecked, this fungus can completely defoliate a rose which not only causes fewer flowers, but also reduces the roses’ ability to survive the winter.

Prevention:
Prevention, of course, is the first step toward controlling blackspot, and the first step for prevention is to buy disease-resistant plants.Keep in mind “resistance” is based on nationwide plant trials, so roses shipped to our nurseries from other states may not perform as well in our area.Consulting local rose growers and/or the Rogue Valley Rose Society can help determine which roses are considered disease-resistant for our climate. For instance, Rogue Valley Roses’ online catalog list disease resistant roses. https://www.roguevalleyroses.com

Also, an article on the OSU Extension website list roses known to be resistant to blackspot in the Pacific Northwest. Those include the hybrid tea roses: Electron, Keepsake & Las Vegas, the floribundas: Europeana, Liverpool, Echo & Play Girl, and the climbers: >Dortmund & Dublin Bay.

The American Rose Society also publishes information on which roses are susceptible to or resistant to rose diseases and you can research this information at: http://www.ars.org. They also post contact numbers for your local American Rose Society.

The next steps toward prevention are proper growing conditions and maintenance. Blackspot needs a wet environment for germination, so you can lessen wetness by providing plants with sun and airflow. Providing roses with suitable nutrients also helps reduce their susceptibility to blackspot by strengthening them.

Prune roses so air can flow among the leaves.
Plant rose bushes with plenty of space between them for air flow.
Plant roses in sunny locations so morning dew evaporates quickly.
Water early in the day, so there’s plenty of time for water to evaporate. Don’t water overhead roses, they just don’t like it!
Plant in well drained soil.
Fertilize properly.

For rose diet click here: https://ashlandorgardenclub.org//rose_diet

Control:
If you are seeing telltale black spots on your roses, then corrective steps should be taken immediately.First, cut off affected plant parts, then rake up all the fallen leaves and discard all of these in the trash in a plastic bag. Diseased leaves should never be composted because blackspot winters over on the leaves, not in the soil; therefore if you compost the leaves you will be dispersing blackspot throughout your garden next year when you spread your compost!

As stated above, air flow is important for controlling blackspot, so while cutting off affected canes, prune to increase air flow through the leaves and between plants. Diseased leaves and canes can be burned, but of course burning is often prohibited in the Rogue Valley,so first call (541) 776-7007 to see if burning is permitted, and remember you will need to obtain a burning permit from the Fire Department.

Treatments:
Sulfur is considered a natural fungicide and it’s readily available in liquid, wettable powder or in dust form. Sulfur does not kill blackspot spores, but prevents a new generation of spores from germinating, so it stops spores from adhering to new emerging leaves. To treat with sulphur, start by pruning off all the affected areas, then spray or dust ALL the leaves and canes. Repeat this treatment every 7-10 days. Sulfur washes off easily, so you will need to re-apply after it rains. Do not spray if temperatures are above 80 degrees and do not use any oil-based product within two weeks of using sulfur. These practices can damage the plant.

When roses go dormant in the fall, spray plants with a mixture of sulfur and horticultural oil. Horticultural oil mixed with sulfur should only be used when the plants are dormant. The oil helps the sulfur cling to the canes during the rainy season, plus it kills overwintering pests. Repeat spraying in the spring before new leaves appear.

Bicarbonates:
Spraying roses with a bicarbonate creates an alkaline environment on the plant which fungus can’t tolerate. This it what makes bicarbonate an effective fungicide. An old home remedy uses sodium bicarbonate (baking soda) mixed with water for treating blackspot,so baking soda has been used as a fungicide for several decades. But recent research shows baking soda is ONLY effective when combined with horticultural oil, and in due course the sodium in baking soda can build up in your soil making it toxic to all plants!

So if you treat your roses with baking soda, you should confine your spray to the plant and avoid overspray. This would help reduce the potential for sodium building up in the soil.The recommended mixture is 4 teaspoons baking soda, plus 1 tablespoons of all-season horticultural oil in a gallon of water. Mix thoroughly and spray on plants early in the morning. Repeat application every 7-10 days. Re-apply after a rain.

Other bicarbonates which can be used are ammonium bicarbonate or potassium bicarbonate. These bicarbonates have the added benefit of providing nitrogen and potassium to the soil which roses need, plus they eliminate the sodium concern. Ammonium bicarbonate has become difficult to obtain and it’s costly, but potassium bicarbonate is available online and at gardening stores. The formula for spraying potassium bicarbonate is 4 teaspoons of powder plus 1 tablespoon of all-season horticultural oil mixed into one gallon of water. Spray lightly on afflicted roses. This solution can be used for powdery mildew and other fungal diseases too, but check the manufacturer’s safe plant list before using on other plants. Spray roses every 10-14 days. Re-apply after a rain.

Warning: Repeated use of horticultural oil over several weeks can cause leaf burn or plant hytotoxicity, especially in warm weather

Organic Remedies:
There are several pre-made organic and natural fungal disease-control products on the market these days, products like Safer Brand, GreenCure, Eco-Smart, Rose Pharm and Serenade. You should consult your local supplier to determine which of these earth-friendly products works best for blackspot on roses. These pre-made products usually contain a sulfur/soap combination or a potassium bicarbonate/oil solution. Just remember even though these products are organic and/or natural they can still be hazardous if not used properly, so always follow the product label’s directions.

Neem oil:
Neem oil is made from the native Indian tree, Azadirachita indica. This oil is considered an organic product and has been gaining popularity with home gardeners.Research shows that Neem oil is successful at killing powdery mildew spores, as well as numerous insects and their eggs, but Purdue Extension reports it is less effective against blackspot. Most Neem oil products that boast blackspot prevention on roses also contain sulfur or potassium bicarbonate.

Chemical Fungicides:
Systemic fungicides are a chemical treatment and therefore they are not organic. There are many brand name systemic fungicides on the market, so consult your local nursery person for recommendations. Systemic fungicides are not sprayed on rose plants, but are mixed with water and poured into the soil. The plant then “takes up” the fungicide through the roots and up through the canes to the leaves preventing the leaves from becoming infected with blackspot.Because systemic fungicides are a preventive it is best applied at the beginning of the growing season when buds begin to swell, then re-applied every 6 weeks. Be aware that some plant specialists state over time plants can become resistant to chemical fungicides.

There are also several chemical fungicides you spray on the plants for treating blackspot on roses, and of course, these are not organic either. These fungicides are also preventative, so don’t wait until you see black spots covering your roses, start spraying your plants at the beginning of the growing season. These sprays are usually applied every two weeks, and as with all toxic chemicals, follow the label’s directions carefully. Do not spray when the weather is hot, as this can burn the leaves. In addition, plant specialists recommend you alternate your fungicides, because over time blackspot can build up a resistance to the one fungicide you’re using.

submit by, Carlotta Lucas

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References:
Rogue Valley Roses https://www.roguevalleyroses.com/

Oregon State University Extension Service
“http://extension.oregonstate.edu/gardening/”>http://extension.oregonstate.edu/gardening/
Purdue University Cooperative Extension “http://www.ag.purdue.edu/extension/Pages/default.aspx”>http://www.ag.purdue.edu/extension/Pages/default.aspx

University of Georgia Extension Service www.caes.uga.edu/extension/habersham/documents/Fungicide.pdf

1.Scott, Judy. (date unknown) Choose disease-resistant plants.
Retrieved from: extension.oregonstate.edu/gardening/node/1072
2. Janna Beckerman (9/07) Black Spot on Roses.
Retrieved from: www.ces.purdue.edu/extmedia/BP/BP-139-W.pdf