Double Knock Out Roses With White Spots & Holes on Leaves

Powdery Mildew

• Despite the fact that Knock Out roses are grown to withstand disease, one ailment that can still happen is powdery mildew. It can be extremely harmful to roses and is characterized by the white spots that form on the leaves. In addition, discoloring of the leaves and other parts of the plant may occur. The mildew is caused by a fungus that infects the plant during the dormant winter season.

Controlling Powdery Mildew

• The best way to stop powdery mildew is to take care of the plant before it contracts the disease. This includes spacing the roses out so that they have enough air circulation, fertilizing the soil and pruning the rose appropriately. If the rose has already contracted the fungus, a fungicide spray should be applied as soon as possible.

Possible Pests

• There are a number of different kinds of insects that attack the rose plant but only a few that would leave holes in the leaves. Two common pests that feed on the rose leaf are pear slugs and sawfly larvae. Both of these insects can be found on the underside of the leaves.

Controlling the Pest Problem

• Although these types of pests are minor problems and will not hinder growth of the plant as a whole, it is a good idea to get rid of them before they reproduce. Too many holes in the leaves of the plant can ruin its appearance. One method is to spray general plant insecticide directly on the visible insects. It is not a good idea to regularly apply the insecticide for a minor pest infestation because it will end up killing other bugs that are an asset rather than a danger.