More beautiful roses without spraying
Tattered leaves on roses are common this time of year. We get lot of questions about how to better care for roses, and what to spray to keep roses their best.
When it comes to diseases on roses, black spot is the usual suspect. Pruning to increase air flow through the shrub, ensuring it gets full sun nearly all day, and keeping weeds at bay will go a long way in limiting the disease.
Insects are somewhat more challenging. There are many insects that affect rose leaves.
They require more work to control, as a gardener needs to do more scouting. Being in the garden at different times of day will many times revel the culprit that is damaging the plant leaves.
Many times, though, there is not enough damage to warrant any controls.
When dealing with any issue on our plants, we need to practice integrated pest management (IPM). This involves scouting for the insects, identifying the insects and then choosing control options. Unfortunately, most people associate “control options” with “spraying.” These words are not synonymous.
Control options can be cultural (such as cleaning up plant debris at the end of the season), mechanical (picking off the insects), biological (finding and encouraging the bad insect’s nemesis), and chemical (which includes organic options).
Goals of a good garden IPM program include:
• Effectively manage pest populations;
• Reduce risks associated with pests (allergies, stinging, biting, disease transmission);
• Reduce the potential exposure of humans to pesticides;
• Educate people about effective pest management;
• Limit potential negative environmental impact;
• Make pest management cost effective.
In the case of rose leaves this year, there were many insects involved. From roseslugs to rose chafers and even Japanese beetles, we had a lot to combat.
The best way to scout for many of these insects is to be up early in the morning to see what is making the holes or go out late with your headlamp on with the red light shining.
Either way, know what insect you are dealing with in the first place.
Japanese beetles can be picked off and dropped in soapy water for effective control. Roseslugs can be controlled by picking off infested leaves.
When it comes to insecticides, reading the label is paramount. To protect the bees, do not spray when pollinators are active. Check for bee activity on flowering plants in the area before you use any chemical.
Avoid contaminating water, as bees use water sources in the area.
Think about why you are spraying, and if there are alternative best practices. Details about protecting bees are on this factsheet: http://go.osu.edu/protectbees
For more information about IPM on roses, visit http://go.osu.edu/roseipm
To learn about bees and pollinators, visit https://u.osu.edu/beelab/
Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County.