When Rose Diseases Aren't
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- WilliamG
- ClaraT
- Mark_Whitelaw
- Mark_Whitelaw
- WilliamG
- ClaraT
- WilliamG
- Mark_Whitelaw
- WilliamG
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» WilliamG - Hey, Mark, I might have discovered something here. I have been
Hey, Mark, I might have discovered something here. I have been complaining of a mystery disease on some of my miniatures which I couldn't really place as blackspot because of one the weather (isn't it a little to HOT for blackspot and most other fungal diseases?) and that it just didn't really fit the description. Well there are several of the mini's which have been experiencing the problem of the ends of the leaves turning brown and looking dry and crisped. I wondered if it was the heat or a fungal disease but now the thought occurs based on the article that it might be a potassium or other micronutrient deficiency because of the quantity of watering which has been required because of the heat?What do you think and how can I add to the soil a potassium additive to test the theory. Do you think this might dictate the regular use of a time release fertilizer or rose food on the mini's in containers because of the required additional watering. I know it is really hot but this has put me in a quandary because not all of the various roses are affected.
William Groth, Houston TX,
USDA zone 9a Upper Texas Gulf Coast
Budding Rosarian (actually a HARJ), Herbophile,
Gardener and Avid Aquarist, Enophile and Genealogist
-- posted by WilliamG
» Mark_Whitelaw - William, Greensand will provide adequate potassium for your r
William,Greensand will provide adequate potassium for your roses, but the use of most time released fertilizers is governed by temperature. The higher the temperature, the faster the nutrients are released.
For now, I would concentrate on keeping your roses alive with water. And although the nutrients will surely be leached away with your continuous watering of containered roses, their NPK needs at this time of year are minimal for your zone.
MarkW>Ft. Worth, TX/Zn 7b, Rose Garden
-- posted by Mark_Whitelaw
» Mark_Whitelaw - Clara, PMJI. Although mites are certainly a possibility, most
Clara,PMJI. Although mites are certainly a possibility, most pest mite species enter diapause (the insect equivalent to mammalian hibernation) when temperatures drop below 50F or exceed 90F. The preferred breeding temperature for the Two-spotted Spider Mite, the most common pest mite, is 70F - where they will double their population in about 14 days.
Since our temperatures here in Texas have been outrageously hot, I suspect the only critter William is defending against is the grasshopper... and even they are smart enough not to come out until the sun goes down.
MarkW>Ft. Worth, TX/Zn 7b, Rose Garden
-- posted by Mark_Whitelaw
» WilliamG - Yes Mark, that probably explains the indication that something h
Yes Mark, that probably explains the indication that something has been munching on the leaves a little bit, but the browning and drying out of the ends of the leaves on certain rose bushes has stumped me completely. It doesn't seem to be terminal and I do see some new growth on some plants. But for me it is a mystery and I have had cats in the house all my life! The curiosity is killing me!William Groth, Houston TX,
USDA zone 9a Upper Texas Gulf Coast
Budding Rosarian (actually a HARJ), Herbophile,
Gardener and Avid Aquarist, Enophile and Genealogist
-- posted by WilliamG
» WilliamG - Mark, Do you know of anywhere there might be pictures of foliage
Mark, Do you know of anywhere there might be pictures of foliage which has been damaged by heat or phytotoxic reactions. What does rose foliage look like if it is "burned" from just succumbing to the elements. If I had some clue I would know whether to try and find different locations for those that get serious afternoon sun in our overly hot weather. Also, on the potted plants, could heat damage the roots and cause the foliage to reflect the damage?William Groth, Houston TX,
USDA zone 9a Upper Texas Gulf Coast
Budding Rosarian (actually a HARJ), Herbophile,
Gardener and Avid Aquarist, Enophile and Genealogist
-- posted by WilliamG
» Mark_Whitelaw - William, I guess I'm going to have to take some pictures of the
William,I guess I'm going to have to take some pictures of these problems for uploading. Right now, I don't know of any available on the internet.
The best example of phytotoxicity I can think of is a brown tip at the terminus ("pointed end") of the leaflet. The brown will travel up on either side of the main rib and usually be a mirror image of the damage on either side.
Heat stress, however, usually looks live severe iron or magnesium chlorosis. Leaves will be extremely yellow or even white. The leaf ribs will likewise be light green.
MarkW>Ft. Worth, TX/Zn 7b, Rose Garden
-- posted by Mark_Whitelaw
» WilliamG - I may do something on the same lines. That is take some picture
I may do something on the same lines. That is take some pictures of the leaves/foliage which are showing the characteristics I am concerned about and upload them to my website or send them as a jpeg attachment to you via e-mail.Actually that might be a worthwhile addition to my rose page.
I have to talk to my other half about taking some more pictures and doing some serious scanning.
Another tack on this question is asked in my heat tolerance query. I will ask what the foliage and canes will look like in cases of heat damage to root systems? Is that as you described for heat stress?
William Groth, Houston TX,
USDA zone 9a Upper Texas Gulf Coast
Budding Rosarian (actually a HARJ), Herbophile,
Gardener and Avid Aquarist, Enophile and Genealogist
-- posted by WilliamG
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