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Landscaping our yard, I went a bit nuts for roses and got a lot of them before I realized how tough they are! Tough to keep happy I mean. My main problem has been rose slugs -- little caterpillars that are really sawfly larvae. They have been really doing a number chewing holes in the leaves, almost killing the plants. I have tried, on various occasions

-- Squishing by hand

-- Pesticides (Neem and imiclopramid I think--"rose spray")

-- Ladybugs

The ladybugs disappeared in 2 days. The squishing is effective but tricky -- once there are old holes it's hard to find where the caterpillars are. I'm not even worried about the ick factor. Pesticides seemed to work but I want to avoid them, and definitely don't want to use all the time.

Is there a secret trick I'm missing? What strikes me as strange is the rose books barely mention them, but they're my biggest problem. Is it a hot/dry place problem? (San Diego here) Do I have to give up on my roses? Are roses one of those things where people love them because they're practically impossible to succeed at? ;)

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  • "Are roses one of those things where people love them because they're practically impossible to succeed at?" That's often been my theory.
    – GardenerJ
    Sep 23, 2015 at 10:55
  • Please send pictures of plants, undersides of leaves, stems, soil, entire plants. To give you advice at this point is pretty irresponsible for our part. There is BT (Bacillus thuringiensis) that is a great, pretty safe and effective product for these guys, IF THIS is your problem. Considered a pesticide of course but it is only the bacterial secretion that if worms/larvae eat they stop eating as they feel full and eventually starve to death. Roses are NOT tough to grow. Need to know their idiosyncracies/pruning, graft protection/proper fertilization. Ladybugs are programmed to leave!
    – stormy
    Sep 24, 2015 at 23:14
  • Thanks stormy, but I'm pretty confident they're rose slugs. I'm in between waves at the moment, but hoping for advice to head off the next one. Unfortunately Bt supposedly won't work since they're not actually Lepidoptera, they're Hymenoptera.
    – CynDiego
    Sep 25, 2015 at 21:42

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Roses, whilst beautiful flowers, are a regular pain as far as I'm concerned. They need spraying every fortnight with a pesticide/fungicide because there's nearly always something wrong with them, are prone to fungal infection, most need proper pruning at the right time to keep the centre of the bushes open to increase air flow, deadheading must be carried out correctly or you get tatty growth, do better if they're manured biennially and fed with specialist rose food twice yearly, look really boring in winter, and on top of that, you get stabbed by the thorns.

You may have gathered they are not my favourite plant and definitely not low maintenance, but if you love them, check out what you can get in your area in terms of the pesticide/fungicide. In the UK, we use a product called Roseclear Ultra, a combined preparation, no idea if its available where you are, but maybe there's something similar. I start the spraying regime here usually in mid April through to end of August, feed in April with Toprose and again in June, and add a manure based mulch twice yearly. Or at least I did - I've been quite successful in getting clients to get rid of their roses over the years, it makes their garden maintenance bills much higher if they keep them.

If you're a retired person, then roses aren't a bad thing to grow - you'd have the time to go out daily and examine all the plants and squish anything you find, and use the milk/water spray in different ratios for mildew and black spot, but this would have to be a daily exercise.

Roses will survive without all this care - but they won't look good and will be infested and infected a lot of the time. I'm afraid, if you're trying not to use chemicals such as pesticides and fungicides, roses were possibly the worst plants you could have chosen.

The link below might be of some help regarding control of rose slug

http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/insects/sawflies/rose-and-pear-slugs-sawflies.aspx

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  • Well, thanks I think :) You kinda rained on my parade here, but at least now I know it isn't me! I have to admit, I have been gradually coming to love my geraniums much more -- at first I sneered at them as boring and common, but they are bombproof and make lots of flowers even with no water and total neglect. Maybe I will let some of my roses succumb... Now I am seeing roses in a new way. For those public gardens with hundreds of plants, they must be just full of pesticides!
    – CynDiego
    Sep 25, 2015 at 21:36
  • Oh, sorry, I know it was something you didn't want to hear - but yes, its not you, its them!
    – Bamboo
    Sep 26, 2015 at 10:39
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Apply Spinosad it seems the only thing that works for me in Santa Cruz. This is my source https://homeguides.sfgate.com/spray-roses-spinosad-sawfly-65711.html

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