Holes in rose leaves

Question: What is causing these holes, and how do I treat them? When isbest time? a.m. or p.m.?

responder: Jane K. If you would like to learn more, please check out these resources.  Replied June 09, 2024, 9:51 PM EDT
response: There are a number of things that could be bothering your roses but this time of year it could very well be a sawfly problem. They are active this time of year and often cause the skeletonizing you are seeing. I am going to provide you with a bunch of links to information sheets as well as suggestions for care. Please read them carefully – they are all short and filled with information. They should enable you to positively identify your problem and decide upon the appropriate action.   Rose Problems.pdf (missouribotanicalgarden.org)  This article from the Missouri Botanical Garden is one of the best for diagnosing rose problems. The pictures are excellent and will enable you to narrow down the list of causative agents whenever you see a problem.  https://www.canr.msu.edu/resources/slug_sawflies  Roseslug or Rose Sawfly | NC State Extension Publications (ncsu.edu)  These two articles describe the sawfly, the life cycle and the damage they cause.   Rose and pear slugs (sawflies) (missouribotanicalgarden.org)  This is also from the Missouri Botanical Garden and covers appropriate treatment for rose sawflies. I’ve printed out some of their advice below. It is important to choose the least toxic solution to any plant problem as you want to target the pest while allowing for the natural predators to continue their good work. A hard spray of water on both upper and lower leaf surfaces will often greatly reduce the population and may be sufficient. Horticultural oils, insecticidal soaps and neem oil are all preferable to the chemical insecticides.   Integrated Pest Management Strategies  1. Check plants for signs of infestation. Early detection can often result in simple cultural control measures. Begin looking for sawfly larvae in mid-spring (rose sawflies) or early summer (pear sawflies). Inspect both the upper and lower surfaces of the leaves. For light infestations, remove the infested leaves and destroy the larvae. A forceful spray of water out of a garden hose can also provide control by knocking off and killing many of the soft-bodied larvae. Be sure to aim the water at both the upper and undersides of the leaves. Continue checking plants throughout the growing season.  2. Support natural enemies of sawflies by responsible pesticide usage. Insects such as parasitic wasps, insectivorous birds, small mammals, and predaceous beetles, as well as fungal and viral diseases all assist in keeping sawfly populations lower. Restraint in the use of pesticides allows beneficial species to assist your control efforts.  3. Use an Insecticide. Chemical controls are also available, but should only be used when necessary, not routinely as a preventive measure. Horticultural oil, insecticidal soaps, neem oil, bifenthrin, carbaryl, malathion, permethrin, cyfluthrin, imidacloprid, and acephate can all be used to control sawflies. Apply pesticides only when larvae are actually present before infestations reach critical levels. Always be careful to read the label directions fully before applying any pesticide, and follow directions completely. Not effective: Bacillus thuringiensis (Bt), a commonly used biological insecticide that offers control of many caterpillars, is NOT effective against sawfly larvae.   Note that it is going to be difficult to know if your treatments have been effective because the leaves are already so chewed. I would suggest a vigorous hosing (top and bottoms of leaves) and then a serious pruning prior to beginning any other treatment. Clean up any trimmed bits and put them in the trash.  Do not allow them to remain on the ground. I did not find any information about time of day for treatment. Common sense tells me it should be mid-morning or so - when the dew has dried and before the heat of the day builds up. Whatever treatment you choose (if any) please read and follow directions carefully. More is not better; it just wastes money and contributes to pollution.   Roses have multitudes of problems and some are difficult to maintain. The best way to have beautiful roses is to get so familiar with them that you can spot any changes. It is far easier to treat a branch than a shrub. Daily visits and visual inspections will go a long way toward finding a little issue before it becomes a big problem. Good luck.

responder: The Question Asker Replied June 10, 2024, 7:32 AM EDT
response: Well, now they are destroying my veggies‼️ Would Sevin end this issue?Getting frustrated here…Sent from my iPad On Jun 9, 2024, at 9:51 PM, Ask Extension <<personal data hidden>> wrote:﻿

responder: The Question Asker Replied June 10, 2024, 3:57 PM EDT
response: Sent from my iPad On Jun 10, 2024, at 3:55 PM, Penny Campbell <<personal data hidden>> wrote:﻿I went out to hose down the roses, as you suggested) and the veggies too. There was a bug on one of the petals. It probably is a saw fly, but I’d like to confirm this from an authoritative source.My late husband, Bob, was the master gardener. He died 5 years ago, so there is no need to express sympathy.That said, if this is, indeed, a saw fly, how should I effectively treat it? Thanks for your patience. It is appreciated.PennySent from my iPadOn Jun 10, 2024, at 7:29 AM, Penny Campbell <<personal data hidden>> wrote:﻿Well, now they are destroying my veggies‼️ Would Sevin end this issue?Getting frustrated here…Sent from my iPadOn Jun 9, 2024, at 9:51 PM, Ask Extension <<personal data hidden>> wrote:﻿

responder: The Question Asker Replied June 10, 2024, 3:57 PM EDT
response: I went out to hose down the roses, as you suggested) and the veggies too. There was a bug on one of the petals. It probably is a saw fly, but I’d like to confirm this from an authoritative source.My late husband, Bob, was the master gardener. He died 5 years ago, so there is no need to express sympathy.That said, if this is, indeed, a saw fly, how should I effectively treat it? Thanks for your patience. It is appreciated.PennySent from my iPad On Jun 10, 2024, at 7:29 AM, Penny Campbell <<personal data hidden>> wrote:﻿Well, now they are destroying my veggies‼️ Would Sevin end this issue?Getting frustrated here…Sent from my iPadOn Jun 9, 2024, at 9:51 PM, Ask Extension <<personal data hidden>> wrote:﻿

responder: Jane K. If you would like to learn more, please check out these resources.  Replied June 10, 2024, 9:02 PM EDT
response: According to the information from the Missouri Botanical Garden fact sheet (see 3 in my original response) bifenthrin is effective against rose sawfly  IF the larvae are actually present at the time of application. Have you actually seen the larvae (probably on the underside of the leaves)?   According to the website Kill over 150 insects - Sevin Insect Killer Dust| Sevin (gardentech.com) the active ingredient in Sevin is bifenthrin. So yes, this should work against the larvae of the rose sawfly IF that is the problem and IF they are present at time of application. Please read the information on this website – it does suggest that morning and evening application is best. And never when the least bit windy.   Your vegetables do not look destroyed in the pictures. They look a bit nibbled. Frankly, I find it concerning if my veggies don’t look a bit nibbled. I do resort to chemicals but only as an absolute last resort. Remember that you are eliminating all the good bugs along with the bad and that the vast majority of the insects you see are either helpful or harmless.   It is also worth noting that the issue with your roses is probably completely different from whatever nibbled on your veggies. Again, identification is critical. I do feel your frustration, but gardening is a long game. There are very few instant cures for any of the problems you might run into and rushing in with a ‘cure’ can sometimes create other bigger problems. Study your problem, identify the cause, and then research a solution. The whole process might take a couple hours but will save frustration in the end.

responder: The Question Asker Replied June 11, 2024, 8:54 AM EDT
response: Thanks for your sage advice. Particularly about the nibbles on my veggies. Again, my late husband was the master gardener, not me.  At this juncture, I’m going to try to refrain from panicking.  I continued Bob’s garden to honor him, and I’m trying my level best. This year, though, it seems as if everything is running amok! Marigolds are being dug up. Sawflies on roses, veggies were being eaten until I constructed more of Bob’s contraptions i.e., tomato cages wrapped in chicken wire to thwart critters. All my work for naught, I fear!  Thanks for your patience, Jane.    From: ask=<personal data hidden> <ask=<personal data hidden>> On Behalf Of Ask ExtensionSent: Monday, June 10, 2024 9:03 PMTo: Penny Campbell <<personal data hidden>>Subject: Re: Holes in rose leaves (#0142014)