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fgilles02420

Rose insect pest control

fgilles02420
17 years ago

This year has been the worst for my roses ever. Many (not all) have suffered from some sort of leaf pest that appears to eat away the green of the leaves, leaving them brown, lacy, skeletonized. (One problem is, I can't actually find any insects, larvae, etc after searching the plant).

After consulting a few rose people it seems the problem is either some kind of tiny inchworm/caterpillar or sawfly larvae. Maybe they've finished their life cycle for now so I'm not seeing them. In any case, I need to develop an organic rose program so I'm here for advice.

So far, my efforts at rose growing have been the same as the rest of my garden, which is mostly perennials: add a lot of compost at planting time, then nothing else. This has worked great for perennials but apparently I could be doing more for my roses.

Here's what has been suggested:

1) Spray early spring with Cornell formula (hort. oil/baking soda)

2) Spray periodically throughout season with neem to control whatever insect it is that's eating my plants

3) Fertilize monthly April - August with some kind of organic fertilizer (alfalfa tea/aged manure/fish emulsion)

4) Add 1/3 c epsom salts 3x season

5) Add a little wood ash to raise pH

6) Prune away dead, damaged wood early spring

Question, if indelicate: can urine be a source of one of the organic fertilizer treatments and if so should I dilute it and how much? Kind of seems like free nitrogen.

By the way I'm not growing sissy roses. Here's the list: William Baffin, Fairy, Bonica, Therese Bugnet, Champlain, Linda Campbell, Constance Spry, R. hugonis and glauca, Felicia, Nymphenburg, Winchester Cathedral.

Thanks for any opinions!

Comments (12)

  • Kimmsr
    17 years ago

    Leaves skeletonized suggest the rose sawfly larva, wee green wormy thingys that usually hide on the underside of the leaves. The Cornell formula will do nothing to combat them, that is a powdery mildew/black spot control. I've not seen that Neem will do much to combat these wee buggers either and since that is a very broad spectrum poison it is not a good idea to simply spray it around in the hopes it will be successful.
    Roses grow best for me, with little to no insect or disease damage if I amend the soil really well with organic matter before planting and be sure they get sufficient water each week. A good soil well balanced with nutrients is best. Never, ever add something to your soil without a good, reliable soil test since adding "something" to the soil can upset the nutrient balance and create more problems than it cures.

  • dchall_san_antonio
    17 years ago

    1) Spray early spring with Cornell formula (hort. oil/baking soda)

    In my book this is an unneeded spray for any but the worst of fungal diseases.

    2) Spray periodically throughout season with neem to control whatever insect it is that's eating my plants

    I would start spraying with milk every 2 weeks. Get the bottoms and tops of the leaves. Milk develops and feeds the microbes living outside the plant which repel (and help the plant to repel) invaders.

    3) Fertilize monthly April - August with some kind of organic fertilizer (alfalfa tea/aged manure/fish emulsion)

    I'm not trying to be a smart a## on this but it sounds like it. Tea is not a fertilizer. It is a source of microbes. Aged manure is really called compost. Once it smells fantastic, it is compost, a totally different material from the original manure.

    4) Add 1/3 c epsom salts 3x season

    Epsom salts is magnesium sulfate. That is a chemical. I supposed it is allowed by the organic standards, but I would not use it.

    5) Add a little wood ash to raise pH

    Do you know you have a low pH?

    6) Prune away dead, damaged wood early spring

    You're a rose guy, right? Don't you prune back 2/3 every spring?

    Question, if indelicate: can urine be a source of one of the organic fertilizer treatments and if so should I dilute it and how much? Kind of seems like free nitrogen.

    I suppose so.

  • fgilles02420
    Original Author
    17 years ago

    "In my book this is an unneeded spray for any but the worst of fungal diseases."

    Could be. But the ARS consulting rosarian who came to my house suggested it for the smothering effect of the horticultural oil on overwintering insect eggs.

    "I would start spraying with milk every 2 weeks. Get the bottoms and tops of the leaves. Milk develops and feeds the microbes living outside the plant which repel (and help the plant to repel) invaders."

    I did a 'net search on this. Everything I've read says milk is a fungicide, like baking soda; it acts by creating an acidic environment where the spores of blackspot and powdery mildew canÂt thrive. DidnÂt find any mention of any insect control properties at all.

    "I'm not trying to be a smart a## on this but it sounds like it. "

    Correct.

    "Tea is not a fertilizer. It is a source of microbes. Aged manure is really called compost. Once it smells fantastic, it is compost, a totally different material from the original manure. "

    You're right; perhaps I should have used the word supplement with regards to the tea. But IÂve read great things about its properties on the rose forum. Thanks for the grammar lesson on manure/compost. I canÂt tell if you approve of using it or just want to be argumentative.

    "Epsom salts is magnesium sulfate. That is a chemical. I supposed it is allowed by the organic standards, but I would not use it."

    According to that definition, table salt - sodium chloride - would be a chemical. Not that IÂd add that to roses, mind you.

    "Do you know you have a low pH? "

    Yes. Very.

    "You're a rose guy, right? Don't you prune back 2/3 every spring? "

    No I'm not a rose guy. First, I'm female. I donÂt consider myself an experienced rose grower at all. So I had an ARS rosarian come to my house for a consultation, and he kindly gave me most of the steps above.

    And, I havenÂt been routinely doing pruning as IÂve tried to grow roses that require only minimal pruning (no hybrid teas here) and I wasnÂt sure what to do. I put that in as another of the things recommended to me.

    Perhaps the "helpful advice" forum is somewhere else. I've been gardening organically for 20+ years, but responses like this make me want to go grab the Diazinon.

  • john90808
    17 years ago

    My feedback:

    I have been diligently spraying the Schultz (Garden Safe) 3-in-1 with Neem weekly since last February. My roses started out looking very healthy up to about early June. I now have the same issue with something eating my roses and leaving the lacy skeletal remains of the leaf. I have not had any issues with rust or black spot. So in my mind, the verdict is still out as to whether Neem will resolve the issue that fgilles describes. I think the Schultz product works well for mildew, rust and the like but it doesn't seem to have any affect on whatever is chewing up my rose leaves.

  • john90808
    17 years ago

    I wanted to post a follow-on to my previous post. I went this afternoon and took a "much harder" look at my rose leaves and did find some green caterpillar like pests hanging out on my rose leaves. I grabbed some liquid Bt and sprayed the plants down. I am using the Garden's Alive Bt product so I am curious as to how it will work on these little buggers!

  • Kimmsr
    17 years ago

    Any plant that is attractive to insect pests is unhealthy and is growing in soils that are not healthy, something is missing, some nutrient. It could just be a necessary nutrient (plants need lots more the N, P, K,) is lacking or it could be that the nutrient supply in the soil is unbalanced and one nutrient is in excess and that is keeping the plant from uptaking others, or maybe the soil pH is not in the optimal 6.2 to 6.8 range and many nutrients are simply not available because of that. But if your plants are under attack from insect pests there is a soil problem.

  • john90808
    17 years ago

    "Any plant that is attractive to insect pests is unhealthy and is growing in soils that are not healthy, something is missing, some nutrient."

    Gee, I guess that makes my entire garden unhealthy. I guess my compost, manure, minerals and organic fertilizers just aren't enough.....by that logic, I bet 99.9% of the gardens in the world are unhealthy.....C'mon, like who doesn't have a pest problem from time to time....it comes with the proverbial gardening territory....

  • fgilles02420
    Original Author
    17 years ago

    I'd agree that stressed and nutritionally starved plants might be more susceptible to insect damage. But plants are insect food! so I don't think you can simply state that all insect foraging is due to some soil deficiency. If that were true with proper soil fertility we could prevent all Japanese beetle damage to our roses, all red lily beetle damage to our lilies, etc.

    Neem was suggested to me; but I've also been reading about a relatively new product called Spinosad, classified as organic, derived from some soil actinomycete. Some information at these sites, if anyone has any actual experience please post:

    http://bexar-tx.tamu.edu/HomeHort/F1Column/2005%20Articles/APR3.htm

    http://www.planetnatural.com/site/monterey-garden-insect.html

    I may try this next year - it seems you have to apply it earlier in the season. For now it seems the leaf skeletonizing pests are gone - new growth seems undamaged. I may just concentrate on water, pruning and fertilizing this year.

  • hitexplanter
    17 years ago

    I used spinosad earlier in the year (May) for a thrip problem I had at the garden center with introduced thrips nailing the new blooms on Belinda's Dream roses and it work very well for that problem. No phytotoxicity were evident after spraying. I will have to look at the label and see if sawflies are listed (not sure). It is now July and I have not had a recurrence of any note since that May spraying. This was in a garden center setting and I needed to deal with the problem and still needed to conduct business and spinosad worked well for my need.
    David a Canyon Lake garden center manager

  • rhizo_1 (North AL) zone 7
    17 years ago

    John, if your green 'caterpillar like pests' are sawflies, Bt will have no effect.

    Spinosad is listed for the control of sawflies. It is also reported to be very toxic to honeybees, just so you know.

  • Kimmsr
    17 years ago

    John, even the companies that sell those synthetic pest control products and fertilzers tell you in their ads that a healthy plant is less susceptible to pests. Why, then, is the concept of an unhealthy plant being more attractive to pests so difficult to understand?

  • pickwick
    17 years ago

    hello...(just visiting)It may be that we are observing the cause and effects of abiotic and biotic stresses under contemporary conditions... Soil mineral nutrition and the health of rhizospheric microflora are important contributors to pest and disease resistance,but one might consider other factors under the heading of climatic changes and its baggage .... Therefore some decent ,though abbreviated peer reviewed websites are : plantstress.com/; The Royal Society (http://www.royalsoc.ac.uk):i.e.insect pests responding to global change);plant pathology online:http://www.apsnet.org/online/features/
    - 1.e., publications for rose growers there....
    suggest a good fine mist sprayer and a good Plant Pathology textbook...