Good morning, I work as a gardener for the City of London, Ontario. We grow about 2000 roses. To control black spot, I have sprayed roses 3-4 times a year with Funginex and Daconil. Daconil has been banned and I thought about spraying with baking soda ( 2g/1 liter) and Funginex. I would like to ask what products are used to control black spot on roses at the UBC Botanical Garden. Thank you very much for your help. Best regards, Al.Szywala
Sorry we have taken so long! Actually, we only grow species roses, great big climbers mostly, and enjoy the fact they do not get black spot and are pretty well disease free!
I have been wary of roses on the coast, since in the South Okanagan they grew all on their own - no worries! However, since Black Spot is such a pest here, I have been doing some research and have found, according to my source, that cornmeal sprinkled on the ground around the trunk will greatly reduce Black Spot. I have no idea if it works, but I'm trying it! (Apparently this is a remedy used by peanut farmers - I have no idea what for!) westgate.
I have made a brew of horsetails, boiled for 3 hours. Once cooled place in a spray bottle, and spray the black spot on the roses. It does eliminate the spots, and is environmentally safe. Good luck. Petals
black spot the last canadian gardening mag. has this recipe:itbsp. baking soda,1tbsp dish soap to 1 gal h20. spray every 7-10 days.I will try it this yr.just thought I'd pass this info along to you.good luck.
Re: black spot Organic blackspot control requires the two pronged approach, 1, upstairs baking soda (sodium bicarbonate) is not nearly as effective as Pottasium Bicarbonate. It works on the same concept of sulphurs by creating a ph level on the leaf lamina that is too hostile for fungal growth. Sulphur will coat leaf lamina with a ph of of 3 ish whilst sodium or pottasium bicarb will raise it to around 9 - 10ish. Pottasium also adds the benefit of toughening the leaf lamina. It is highly effective against powdery mildews and is used to great effect in organic vineyards. It wont burn foliage either. 2, downstairs removing fallen leaves from blackspot atack is necessary to eliminat the fungal growth cycle. Spores develop one the leaf is undergoing the early stages of decay. I have neither the time or inclination to practice rosebed housekeeping. A far more effective method of managing rose cultivation is to mulch fortnightly with premium lucerne hay. this will cover any fallen leaves and hinder the ability for spores to rise. The decaying process of lucerne encourages the whole gammett of composting organisms which devour the diseased leaves with gusto. Spread enough lucerne "HAY" NOT CHAFF, to cover leaves and ground. You've now done two jobs at once leaving you with a few more hours in the day to darn some socks or whatever else takes your fancy. Check out this australian website for products. http://www.ocp.com.au/OCPWeb/products/EcoCarb.htm
There is a new product called Serenade available in the USA this year. It is registered for organic use for the control of blackspot. You could check it out. I've heard that baking soda is not very effective on blackspot but is good for powdery mildew.
hi Baking soda may work/or epsons salts but if you go with the clean /up of the ground and if posssible keep them from direct rain . With roses the shinier the leaves the less affected they will be.(generally speaking) Are you sure ( have you had it tested) that it is black spot or maybe shotgun virus. Do you mulch with cow/steer manure? Regards Doug
Hi Doug, My anecdotal evidence of the effectiveness of POTASSIUM BICARBONATE not sodium bicarbonate against black spot fills me with great confidence. My "Lab Rat" is my mum's favorite rose "Just Joey". It's a sucker for black spot in our climes and is always first to succumb. I sprayed half the bush fortnightly for 18weeks last year and was thrilled with the result. The neglected side defoliated and lost vigour whilst the other side kept a substantial crop of healthy leaves with evidence of limited balck spot attack. I maintained my practice of applying a layer of lucrne hay to cover the fortnights fallen leaves to disrupt the fungus lifecycle during the season also(You're mad if you don't practice this method). I'm unsure whether the additional foliage feed of Potash strengthened the leaf to resist attack or whether the dramatic ph increase was the effective factor. Regardless, forget using baking soda and soource potash soda. be careful of overuse of epsom salts as you could unleash a whole new set of soil problems to deal with As far as my mum is concerned, her Just Joey without blackspot has secured my position as #1 son.
I would recommend liquid sulphur as a control and as a preventative. The best approach is to stop it before it starts. Do you use winter oil in the fall and spring ? You might contact your suppliers about sourcing sulphur and oil or just contract the care out to a spraying company with a large sprayer if you don't have one yourself. The high temperatures of the summer will help you but the high humidity will counter that. Daconil had some residual but sulpher does not. Fortunately it costs less for the material but it costs more for labour because you will need to use it every week likely.
Thanks a lot Mr. Mosquin for the information.I also use 'potash' as one of my plant fertilisers.Is this the same as potassium bicarb you're talking about or something diff.?
Possibly - apparently the term [WIKI]potash[/WIKI] has become somewhat ambiguous. Is there a label on the potash that you use that gives its chemical contents?
