How do you control greenfly (aphids) on roses?

General Discussion
1

I have noticed a few times that posters on this forum say they don’t use harmful insecticidal chemicals on their roses. I am wondering what techniques you do use to combat greenfly (aphids)?

At the moment I am doing the very time consuming job of removing them by hand, and using a small spray bottle of water, and a very small paintbrush for delicate leaves. I was hoping to introduce ladybirds (ladybugs), but haven’t had much luck with them so far, maybe partly as it might not be warm enough yet, though this afternoon my garden thermometer was showing 20 degrees Centigrade (68 degrees Fahrenheit), and I haven’t seen it fall below 11 or 12 degrees Centigrade (59 degrees Fahrenheit) in the past few days, though I haven’t looked at about five in the morning when the temperature will be coldest.

I have tried both adult ladybirds and ladybird larvae (Adalia bipunctata) with no luck yet.

I have read all kinds of suggestions, like using washing up liquid (dish soap), or essential oils. The essential oils didn’t work, and don’t seem gentle on roses either, and clogged my spray bottle though I did manage to unclog it by cleaning it.

Are there any good techniques to remove greenfly (aphids) by hand, as quickly as possible and without harming the rose plant?

I noticed a lot of ants in my garden this afternoon too, all over my rose bushes.

The strategy I have been trying is to pay a lot of attention to delicate rose trees, and other delicate plants like cyclamen seedlings, but leaving a few rose bushes with greenfly on them in attempt to attract ladybirds or anything else that might eat them. It is a lot of work, as the greenfly keep coming back, and there seem to be two types, including those with wings which seem to be laying the eggs. The rose bushes that I have left the greenfly on have no flower buds yet, and the ones I have paid attention to removing the greenfly are covered in flower buds that are beginning to open. That could be coincidence, or maybe greenfly infestation seriously damages rose bushes and stops them flowering?

We have a tree that used to be home to a lot of house sparrows, who up until last year seemed to keep greenfly at bay, but recently somebody in the neighbourhood got a huge cat, about twice the size of ordinary cats, very beautiful with tabby markings, I think maybe a Maine Coon, who climbs on the roofs and everywhere, and the sparrows haven’t come back this year, I miss them.

I wondered how other people control greenfly (aphids)?

2

Use to spray with dimethoate, for birch miner and fall aphid hatchling hordes … decided thats a losing bet. If l did not protect well enough l felt its effects. Decided Let nature do its thing 15 years ago. I stop spraying any of the garden even with insecticidal soap and other home remedies.

Now naturalized lady bugs have the aphids in balance (check) and have not had an aesthetics or wilt problem with roses. This year l did an informal count after they re- emerged from hibernation and it was 2-3 per sq. ft.

However now another imported invasive insect scourge has shown up and it is killing the cotoneaster hedging in town. Oyster shell. Back to now malathion spraying just the hedging and before the end of May. l have a 125 feet of it and in no mood to lose it.

3

The rose immune system keeps aphids in check.

Title: DYNAMIC ASPECTS OF THE CHEMICAL RELATION BETWEEN THE ROSE APHID MACROSIPHUM-ROSAE AND ROSE BUDS
Author: MILES P W

Author affiliation: WAITE AGRIC. RES. INST., UNIV. ADELAIDE, ADELAIDE, S. AUST.

Published in: Entomologia Experimentalis et Applicata, volumn 37, pages 129-136, (1985).

Abstract: “Dynamic aspects of the chemical relation between the rose aphid [Macrosiphum rosae] and rose buds.In warm weather, M. rosae (L.) walks off buds of hybrid tea roses during a critical period coinciding with the opening of the sepals. This behavior could not be related to histologically detectable barriers to feeding, nor to changes in the water content of the tissues or in their composition with respect to total soluble carbohydrate, amino nitrogen or phenolic compounds; major changes in tissue chemistry, effected by spraying the bushes with urea, did not affect the time at which the aphids left the buds. Tissue sap expressed from stems and sepals showed a significant increase in catechin content after, rather than during, the critical period. Once expressed, however, sap from buds at the critical stage showed a sharp in vitro rise in catechin content over a few hours, up to levels approximating those against which the insects discriminated in choice tests. The insects could well be sensitive to a developing capacity of tissue to accumulated catechin, possibly in response to their feeding activity.”

https://www.researchgate.net/publication/230314125_Dynamic_aspects_of_the_chemical_relation_between_the_rose_aphid_and_rose_buds

4

Thanks for the interesting replies.

What I find strange is that the Mexican fleabane (Erigeron Karvinskianus), or Mexican wall daisies, that I have in my garden don’t seem to get attacked by greenfly (aphids) at all. About the only plant that doesn’t, though the spring flowers like primroses and bulb grown flowers don’t get attacked either. Right now I have a real infestation, and they don’t seem to have any predators, though there are a lot of spiders and webs I don’t know if spiders are much good against aphids.

I remember once noticing that if I used a product with a lot of seaweed in it, plants toughened up and didn’t get attacked by anything, even the slugs left them alone.

5

I use a couple drops of dish soap in a spray bottle and just fill it with water. Cheaper than buying insecticidal soap and works just as well. Of course it requires multiple sprayings each time you see them, but it has worked for me. If any plants have mildew I just add a little baking soda.

Duane

6

Thanks for that suggestion. I have had a massive infestation on almost everything, and a few quite expensive things I tried failed.

I don’t know if this will work yet, but today with a few of my rose bushes and other plants with long flexible stems I dunked the stems, leaves, flowerbuds and all into a 500ml yogurt pot filled with my washing up water (dish soap water after doing a few dishes). Loads of aphids (greenfly) fell off into the water. They now look like they have had a good clean, and flower buds that were covered with aphids are now visible. A couple of times I broke stems, but it doesn’t matter as these are big bushy plants that need a bit of pruning anyway. Much quicker and easier than trying to spray undersides of leaves that were absolutely covered with aphids.

This won’t work on everything, some of my rose bushes don’t have long flexible stems so I can’t bend them into a yogurt pot of dish soap water. I will have to use other methods on my miniature roses with shorter stiffer stems. But at least the garden isn’t a huge reservoir of aphids as the big plants have been cleaned, so there are less aphids to keep landing on the delicate little plants, which I was having to tend twice a day to remove them.

Also, it might have harmed my plants, I don’t know yet as I only did this today.

7
8

I noticed that a big bed of Feverfew that was heavily infested with aphids (greenfly) now only has a few. My roses still have quite a lot but maybe not so many. I have applied loads of ladybirds and ladybird larvae, to the roses, which just seemed to disappear. I also a few weeks ago probably overdid the SB plant invigorator, which I think is like a horticultural soap with added foliar iron and a few other things. Some leaves got a bit brown afterwards, but I probably applied it too often, and stopped using it a few weeks ago, for a while.

I did wonder if the ladybirds migrated from the roses to the Feverfew. Also I have found a lot of these black beetles in my garden, on the Feverfew and also on the Mexican wall daisies (Erigeron). And I also today spotted what might be a ladybird pupa hanging off a Feverfew flower. I also noticed one on a pipe.

Here in the UK we had such a cold spring that I think garden flowers are at least a month behind, if not closer to two months behind, and maybe aphids do naturally lessen in summer? My aubretia are only just starting to flower now, and they should have flowered in spring.

My Blue for You rose is flowering beautifully, and though it did get a few aphids especially a few weeks ago, it doesn’t seem to get them too badly and looks ok at the moment. I didn’t apply any ladybirds to that part of the garden either. I also overdid the SB plant invigorator on it a few weeks ago, and it survived that really well. An amazing, beautiful and tough rose. (Its flowers don’t droop, they hold up, and the plant itself is strong and has coped with wind and rain without flopping over, its form is wonderful, and I have had so many other roses that can’t hold themselves up properly).

Does anyone know what this black beetle is, and if it eats aphids?
E6DEFB2E-EC30-4A7B-959B-FE2561B3A743.jpeg

9

Is this a ladybird pupa?
542706B4-AB51-4CA4-BB0C-B060D7354F02.jpeg
409F8094-FA36-4FC6-8848-66C31F299E65.jpeg

10

No home gardener wants to admit to having an ant problem. But ants are everywhere, and for the most part, they’re harmless. They fall into the same category as spiders and mice: they’re pests you can tolerate in your life so long as they stay out of your way. They won’t make a habit of visiting your garden if you’re lucky. Ants will take all the food you leave out on your porch overnight. Still, they aren’t particularly interested in plants unless they can smell sugar nearby. Anyway, the pieces of advice that I found in an article about “How to get rid of ants in bathroom” helped me to get rid of them.

11

Ants “farm” aphids and other sucking insects for their honey dew, the sugar water resulting from their sucking and digesting plant sap. Ants will literally remove them from the upper parts of the plants and put them under ground on the plant roots when conditions are too severe for the sucking insects. Ants will often colonize in the roots of plants in the ground as well as in pots, seriously disturbing the soil around the plant roots which interrupts their ability to absorb water. If undiscovered during periods of extreme weather this can literally cause the loss of the plant.