DIY: Bugs That Eat Roses
- 1). Examine the rose leaves for a sticky black substance, especially in the cool temperatures of spring and fall. You might also notice the foliage drop prematurely. Aphids cause the damage as they feed on the plant's fluids. The pear-shaped insects also release honeydew, the sticky substance that ends up black when sooty mold transfers to the bush attracted to the excretion. Aphids are 1/8 inch long with a green or pink soft body. You find them on young buds, leaves and shoots. Keep the garden pesticide-free to attract parasitic wasps and ladybugs, for example, which are some of aphids' natural predators. Remove the insects with strong jets of water. Spray them directly with insecticidal soap, a low-toxicity pesticide option. A large number of strong synthetic chemicals also exist to control aphids on rosebushes. Use them as a last resort. They include bifenthrin, cyfluthrin and esfenvalerate among others. Apply them according to the product label.
- 2). Treat the plant for Japanese beetles if you notice widespread destruction of the shrub and metallic-green, hard-bodied insects on the plant. The Japanese beetles favor the flowers, but also feed on the foliage, with the potential to leave the bush naked. Handpick and drop the bugs in a bucket of soapy water. As a last resort, spray them with an insecticide containing carbaryl, diazinon or acephate. The chemicals kill the beetles you spray, but it does not stop new ones from flying to the plant. Besides, when insecticidal mist lands on the flowers, it kills the bees that come to feed on nectar.
- 3). Blow gently on rose blossoms that never fully open before turning raggedy. Look at the flowers and foliage immediately afterwards to confirm a thrip infestation. The insects are very small and difficult to see. When you blow on the plant, the little bugs move around, making it easier to notice them. The damage thrips cause is the result of their sucking the sap. Prune the flowers and leaves affected. Weed around the plant to keep the area free of host vegetation, including grass. Spray the thrips with insecticidal soap at the frequency recommended on the product label. As a last resort, use a stronger pesticide containing acephate, bifenthrin or cyfluthrin, for example. Insecticidal treatment is most effective when you spray the closed rosebuds before the insects penetrate them. Your county cooperative extension office or a local nursery might have an estimate of when thrip activity starts in your region.
- 4). Diagnose the rose shrub as suffering from a case of spider mites if the foliage becomes gray or bronze. The mites are very small spider relatives that congregate in large numbers on the underside of rose leaves to suck the sap. Hit the bottom of the foliage every two days with a strong jet of water to remove the pests. Spray them with an insecticidal soap if the problem persists. Use it at the frequency recommended on the product label. Mites reproduce quickly. If the infestation gets out of control, try a synthetic pesticide containing the chemical dicofol, applied according to the manufacturer's instructions.
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