Rosie's Corner: Strategies for managing rose pests

Bugs!

Have you started getting them yet? I killed a couple of aphids the other day. The weather situation is perfect for their breeding. What is an aphid? They are little critters that can multiply very quickly and cause damage to your plants. They have a long slender mouth part that they use to pierce stems and leaves and suck out fluids. Something you really don't want on your tender rose plants (or any other plants).

Do I spray insecticides for them? Nope! I grow my roses in a no-spray garden. There are a couple of ways that I get rid of them. One, I hit the plant with a strong blast of water from my hose. Make sure you spray the underside of the leaves. That will knock the little buggers to the ground, and they are too lazy to climb back up. Two, I squish them with my fingers. Now don't go euuuwwwwww! It works! Use gloves if you wish. Three, I have California native plants in my yard. They attract beneficial insects like ladybugs who love to feast on aphids. So, try doing these things to help remove aphids in your garden.

I saw my first Hoplia beetle this week, so I know they are here. They love the Central Valley. A lot of people think that they are Japanese Beetles. Totally different insect (which we don't have in Fresno, thank goodness!). Hoplia beetles love light colored roses. They usually arrive late March and last until May. Then they are gone until next year, unlike Japanese beetles which go through several breeding cycles a season.

Hoplia beetles start as grubs in the soil. They grow slowly over the winter and then come out of the soil in the spring. They love to eat the flowers of your roses (their preferred diet) but will attack other flowering plants as well. You know you have them if you see holes in the petals of your roses. They will often hide in the center of the flower.

The best way to handle them? Pick them off with your hand and squish them or drop them in a bucket of soapy water. I have never been able to master the soapy water trick (I need a third hand for that), so I don leather gloves and squish them! Since they like light-colored roses, planting dark-colored roses might be helpful. You can also just cut off the flowers and dispose of them.

Unfortunately, sprays don't work to kill these little buggers. They love to hide in the interior of the blossoms, so it is difficult for the spray to get on them directly. If you do choose to try to use an insecticide to kill them, do not do it when bees and other beneficial insects are present as it will kill them as well. In about six weeks or so, the beetles will be gone for another year. One must have patience as a gardener. Dealing with Hoplia beetles is a good lesson in patience. By the way, I do try to get out and squish them twice a day. Once in the morning and once in the evening. It's an effective way to check on my garden and it is a great way to unwind from the day.

It is also time to check for spider mites, or The Spidey as I call them. They can cause damage to your plants very quickly. Check the undersides of the leaves of your roses for very tiny rusty-colored bugs and tiny webs. Give them a good strong blast of water from your hose. It will help to remove them. Keep a close eye on your plants to make sure they are gone. Beneficial predators such as lady bugs and lacewings will feed on them (another reason to have California native plants in your yard!).

If you choose to use a chemical for spider mites, both horticultural oils and soap will work. Insecticides don't work on spider mites. They are a mite which is different species. So, check the label to see if the designation, “miticide,” is present. Pesticides claiming they are “for mite suppression” are usually weak and will not perform well or will require multiple applications.

Do not use them when bees and other beneficial insects are present. Do not use a dormant or horticultural oil when it is going to be over 80 degrees that day as it can burn your plants. Don't use it if it is going to rain. If you are going to use these chemicals, you must dress the part and use eye protection, a face mask, gloves and preferably suit up. Dispose of any leftover chemical properly and wash up/shower afterward (including washing your hair).

Fungal diseases

OK, enough about bugs. I shall touch briefly on fungal issues. Check your roses for botrytis. If you see fuzzy brown or gray areas on your buds or leaves, chances are it is botrytis. Normally we don't get fungal diseases here, but we have had our share of rain this year. I don't use fungicide. If I see a rose bud or leaf with botrytis, I cut off the offending part (aka, leaf or bud) and dispose of it. I make sure I have air circulating around my rose bushes and that they get the necessary sun to grow. I am on a drip system, but if I used sprinklers, I would only run them in the morning so the leaves have time to dry. I make sure there are no dead rose leaves under my rose bushes as they can harbor fungal diseases.

Another fungal disease you might see on your rose bushes is black spot. It looks just like the name says, black spots with sometimes feathery margins on your rose leaves. The spores of this fungal disease spread by splashing water, so don't sprinkle your rose plants at night. There are also rose varieties that are black spot resistant. So, look for those if black spot is a problem in your garden.

Another, more common, fungal pest is powdery mildew. It shows up as a white patch of spores on your leaves. The best way to control powdery mildew is prevention. Grow your roses in a sunny location. Don't use the sprinklers at night.  Clean up dead leaves around your rose bush as the leaves can harbor the spores. Click on the hyperlink to find out more.

When your roses have completed their first bloom, it will be time to deadhead and feed them. You should get a nice second bloom about six weeks after the feeding.

My first rose to bloom this year

Alice Hamilton! This antique rose is named after Alice Hamilton who was an American physician, research scientist and author. She was a leading expert in the health field and is considered to be the mother of occupational health in this country. This during a time when women could not vote! She became an M.D. at age 24 in 1893 when she graduated from the University of Michigan Medical School. She was the first woman appointed to the faculty of Harvard University in 1919. I could go on and on about this amazing woman, but I hope you check out her bio and her rose.

Until Next Time…”Teaching you how to grow a garden is better than giving you a thousand roses.” Matshona Dhliwayo