Also serving the communities of De Luz, Rainbow, Camp Pendleton, Pala and Pauma

Sunshine brings out roses and pests

Frank Brines

ARS Master Rosarian


This year continued the signs of climate change with below-average temperatures and above-average rain and snowfall as well as chaotic weather patterns nationwide. Rose growth and development are dependent on weather, and flower production is particularly impacted by inconsistent temperatures, sun and water.

All of this has made it more difficult for me to predict what to do and when to do it. Typically, the first flush of blooms is expected after eight to 10 weeks, usually on the longer side. This year it was 10-11 weeks. In this area, the first annual rose shows was April 22, and local exhibitors had fewer roses for the shows.

The longer time frame for rain and cool nights set up the environment for some rust, mildew and botritis fungus. A few applications of fungicide spray would help to reduce or delay the outbreak.

But now that we've seen the return of abundant sunshine we're seeing larger blooms – so I hope your roses are starting to surge. If you didn't apply fertilizer earlier, be sure to do so soon (more about this a little later), along with plenty of water to maintain this production curve.

A few hot windy days can quickly evaporate ground moisture, especially if you don't have at least a couple inches of mulch spread in the beds. Know the soil composition in your garden so you know how much water to apply to maintain good soil moisture without drowning the roots – or wasting water.

Be vigilant for changes, diseases, and pests in your garden now and be prepared to act on these immediately. The Hoplia beetle appeared in April with just a few hot days. I usually see this beetle in May. I think we can now expect it in April, so mark that on your 2024 calendars for their appearance.

They can do serious damage to rose blossoms in no time, starting on light colored varieties. The Hoplia is easy to remove: Just drag it out from between the petals with a screwdriver or Q-tip and plop it into a cup of sudsy water. (Note: To learn to identify Hoplia beetles, just do a search on the internet. Bottom line however: If you find little holes in light colored petals, and you find beetles nestled between the petals, you've probably got Hoplia – dig 'em out.)

[CAPTION: The Hoplia beetle damages petals.]

Another early visitor is the spider mite. Damage can happen well before the casual observer will notice it – so look closely: Inspect the underside of the leaf and look for tiny black granules, and if you run your finger lightly over the underside of the leaf it will feel gritty.

You can also try holding a sheet of paper under the leaf and shake the leaf or scratch them onto the sheet of paper. If you miss the first phase you will see an unusual mottling of the leaves as seen from the top of the leaf.

[CAPTION: Look for signs of spider mites.]

Blooms mature quickly in warm weather so, as they fade, lightly prune back to the first outward facing five-leaflet leaf. Try to shape the bush to outward facing buds. If you can, retain canes that are larger than the diameter of a wooden pencil. Doing this now, your next blooms will appear around mid-June before the summer heat. Make sure to put all pruned-off vegetation into your green waste barrel.

Roses want a constant supply of nutrients, including micro-nutrients such as copper, iron, manganese, magnesium, as well as macro-nutrients such as phosphate (P) and potassium (K) which help develop strong root systems, better blooms, and prevent stress during adverse conditions.

Remember that you are also feeding the soil microbiome which is complex and multi-tiered, abundant in beneficial microbes which create a sustainable soil diversity acting like an immune system.

Try avoiding chemical fertilizers which harm your soil ecosystem. Plants grown with organic fertilizers are themselves more resistant to pests and diseases. If you feel that your efforts are failing at getting the right type and mix of nutrition for your garden, you might find that a soil test kit for analyzing the soil's needs helps you choose the right treatment.

Organic amendments such as manure, compost or mulch stay where you put them, break down slowly, don't contribute to groundwater pollution (as long as you prevent run off into drains), improve the soil food web, so that in the long run you end up using less product while providing "food" for all the creatures like earthworms who act like rototillers mixing them into the soil to lower depths.

It is never too late to apply a thick layer of mulch. Mulch keeps the entire bed uniformly supplied with water. Use composted mulch, not wood products. (Pine needles are good too.) Apply to a depth of 3 to 4 inches.

Avoid mulch containing wood chips because, as they break down, they rob the soil of nitrogen, and they can become a medium for fungal growth that is impenetrable to water, fertilizers, and oxygen.

Keep an eye on your garden for water stress, insect pests, and fungal diseases. Do not use a formula that treats everything. Use only a product especially for the specific problem, follow the directions and dose rate carefully, and treat in proportion to severity, as well as your level of acceptance. If control is lost, it may be necessary to strip off all of the diseased leaves and prune back and basically start over.

Some organic formulas use neem oil, insecticidal soaps, baking soda, etc. Read entire labels and use according to directions, including safety equipment to avoid exposure to contaminants. Keep your skin covered when applying chemical treatments.

Use approved goggles for eye protection, respirator mask, long sleeve shirt, water/chemical resistant boots and gloves. When the treatment is completed, immediately remove clothing and wash. Take a good shower to remove any possible contamination.

Over the past decade or so, Southern California gardens have been showing an increased prevalence of the fungal disease "Black Spot." It appears as dark green to black spots on leaves, which often turn yellow and fall off. The infected leaves (even those that drop) produce spores that can infect other leaves. There are many fungicides available, but control can be difficult. Sometimes you just have to remove and dispose of any affected leaves.

Another new pest in our region is the Chilli Thrip. Some gardeners are reporting Chilli Thrips in their gardens already. I have seen some evidence of thrips too. It's much smaller than the Western Thrip that we're accustomed to and more devastating as it eats all varieties of vegetation.

Control is quite difficult and new treatments are being studied. Products containing Spinosad bacteria seem to help control soft-bodied larvae, but be aware that even such "natural" products can kill other (beneficial) insect species.

I've grown many varieties of roses in my gardens. Most will grow well in the Temecula Valley. Some varieties I recommend, Mr. Lincoln. Outta the Blue, Easy Does It, Touch of Class, Double Delight, Joey, Gold Medal, Graham Thomas, Fragrant Cloud, Fragrant Plum, Sunsprite, Playboy, Sally Holmes, Ballerina, Tropical Lightening, Hey Jack, Neptune, Violet's Pride.

Heads up for high summer: Don't expect great roses during July-September when temperatures are high. Just keep plants well hydrated, and remove just spent petals, leaving the "hips" (don't prune). The plants will enter a short dormancy and build strength for fall. Look for more information here next month.

I am an ARS Certified Master Rosarian; that means that my mission is to spread the knowledge and love of roses – for free. If you would like personal answers to questions, you can write to me at [email protected].

And when you've got a moment to spare, go visit Rose Haven, located at 30592 Jedediah Smith Road (the cross street is Cabrillo Avenue) in Temecula. Also, visit


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