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ROSE CARE FOR JUNE
by Betty Mott, Consulting Rosarian
by Betty Mott, Consulting Rosarian
In the past month I have traveled to Sacramento, San Jose, the Peninsula and San Francisco to judge the annual spring shows held by local societies. I honestly felt that my roses were doing so well because of mind-full pruning, soil amending, alfalfa pellets, squishing copious amounts of aphids and curculios and adding a good layer of mango mulch. The truth is that everyone’s roses are doing great this year. I am hearing the same stories from rose gardeners everywhere. Gardeners who did not get around to pruning their roses this winter and stories about neglected roses on their last roots have been blooming like crazy with shiny green leaves and new basal breaks. So what is it that made this year such a banner year for roses? Was it the late rains, unusually dry January, winds, or maybe the cold spells? There is no clear explanation but only a reaffirmation that every year brings different weather conditions that control our gardens. We are only along for the ride that Mother Nature takes us on each year in our gardens.
Yes, it was sad to see all the blooms nodding over with the weight of the May rains, but look at the lush green foliage and think about how much water was saved (of course I had just programmed my drip irrigation system only to have to run out in the rain to shut it down).
Shortly after the rains you might have noticed tiny red spots forming on your otherwise beautiful blooms. Unfortunately, blooms full of moisture can lead to Botrytis Blight. This rose disease finds its way into the garden early in the season and also in the late fall under cool wet conditions. Spores are moved to roses by air currents or blowing rain. I consulted the Marin Rose Society website and gathered the following information from an article written by Nanette Londeree.
The disease is caused by several strains of the fungus Botrytis cinerea and produces a range of effects. Flower petals become spotted or discolored, flower buds may fail to open or the buds may rot, leaves and shoots discolor, wilt, decay, and drop and twigs may die back. The symptomatic spots that look like water spots start as tiny, almost translucent spots; they are caused by the plants’ reaction to the invasion of the fungus.
The disease thrives in warm, humid conditions; its optimal temperature range is 70 – 77 F, though it is active over a wide temperature range. The fungal spores can germinate and result in new infections after six or more consecutive hours in contact with free water – from splashing, condensation, or high relative humidity (greater than 90%). It survives in decaying plant material or on the soil surface and can over winter even in cold climates. It can remain dormant until the weather conditions are right, and then spring to life.
Since it is such a prevalent fungus, prevention is the best approach. Provide good cultural care to your plants and maintain your garden sanitation - clean up and dispose of fallen leaves and debris to minimize the reservoir for future infection. Prune out dead or dying tissue and thin the plant canopy to improve air circulation. Most importantly, avoid overhead watering, or if it is necessary, water in the morning so that plant surfaces have adequate time to dry. Fungicides like chlorothalonil (Daconil 2787, Fungi-gard), or mancozeb (Fore) are generally not effective in environmental conditions that favor the disease (wet foliage), and are only preventive, not curative. Also, this disease is notorious for rapidly developing resistant strains, so if you spray, it is important to alternate spray materials. Use caution when spraying and follow the directions on the product label.
Up until last week, we had successfully warded off the deer in my front yard by using Repellex tables—a unique, non-toxic, systemic animal browsing repellent tablet. Tablets are placed in direct root contact, discouraging animal browsing damage to roses for up to three years. When absorbed by the root system, this tablet imparts a bitter taste to the rose. The product is non-damaging to the roses. While nervously watching neighborhood rose buds devoured to a nub, I was thrilled with my success. Yes, the deer did sample a few blooms, but seemed to move on by to other rose gardens.
It was a stunning oversized bloom of ‘Leonard Dudley Braithwaite’ a David Austin Shrub, (dark red, very double, 1993), which I chose not to bring to the annual show in Corte Madera so I could marvel upon it for days that also caught the attention of the deer. The bloom was just beyond my carport railing so Repellex tablets were not placed under that rose bush. Unfortunately, I had underestimated the reach and determination of deer. After feasting on L.D., the deer noticed all the other goodies and somehow blasted through the bamboo fence, crushing my lettuce plants, nibbling on this and that, left a pile of calling cards, and with one final burst to get out jumped onto my large green composter crushing the top, leaving hoof imprints in the metal, before its grand exit.
Fortunately, the exiting experience seemed to be enough to deter the deer for the moment and more Repellex tablets were added to the remaining vulnerable roses. My husband reminded me that the deer actually did me a favor by waiting until after the annual show.
After your first bloom cycle, it is a good time to think about adding fertilizer to your roses. Following Tom Bonfigli’s advice one could head on down to any garden center and look for any fertilizers that have been marked down. For rose gardeners looking for an organic approach and knowing that our Rose Garden in the Marin Art and Garden Center has been recently designated as “organic”, I consulted with Master Gardener and Consulting Rosarian John Goldsmith who worked with Charlotte Torgovitsky to develop a formula for use in the rose garden. John mentioned that they are still tweaking the ingredients, but was happy to share what they have developed so far. Since I managed to fill one 33 gallon garbage can with rain water from the May storm I have decided to give it a try. I plan to use Maxsea (my usual rose fertilizer) on my front garden and John’s Organic Rose Compost Tea (10 Cups - Alfalfa Pellets, 2 Cups - Epsom Salts, 1 Cup - Liquefied Fish Fertilizer, 1 Cup - Liquefied Seaweed Fertilizer) on the roses in the back yard and observe what happens.
Aphids and spittle bugs have disappeared, but I still hunt daily for Curculios although numbers are decreasing and will soon disappear until next spring. I find myself doing a walk through the garden a couple times a day, squishing any I see and removing any drooping buds to reduce next years population that are setting up in the damaged buds. Remove leaves with black spot and rust, placing them in the green can, NOT the compost. Continue to deadhead to set up the next bloom cycle of your roses. Some rose gardeners just snap off the heads of the spent blooms while others looking for sturdier stems go down the cane leaving at least two sets of five leaflets and cutting to an outside facing set.
This is also the time to prune the one-time bloomers immediately after flowering. For maximum blooms, give them more of a light grooming than a severe cutback. Prune only the previous year’s growth. On older established roses prune back some of the oldest canes to promote the development of new stems near the crown or for grafted roses the bud union.
I would like to applaud our five novice exhibitors; Don Chapman, Paul Cullen, Sara O’ Keefe, Thom Uelk and Anne Marie Walker who collectively brought in more than 20 blooms to our annual show in Corte Madera. I also encourage you to share your blooms at our monthly rose shows.
In closing I would also like to share a quote with you sent to me on a bookmark from my daughter:
- “I’d rather have roses on my table than diamonds on my neck.” – Emma Goldman.
My daughter knows me well !
A YEAR OF ROSE CARE:
January
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Last Modified: 6/30/09