Common Rose Pests - Part 2: Mites and Scales
an additional pupal stage, followed by a resting phase, before becoming a winged adult. Although males don't live very long, the entire scale's lifecycle, from egg to adult, can range anywhere from 60 to 120 days.
Damage: Scale attacks commonly appear as yellow or brown spots or streaks on leaves, almost as if the damage were from a viral disease. Don't be fooled! Severe infestations may cause poor growth and subsequent incrustations on both leaves and stems. They can kill your rose!
And if that isn't enough damage, Soft Scales also produce honeydew, and as such attract ants much like their cousins, the aphids. This honeydew also provides a growing medium for "sooty mold."
Control: I don't want to discourage you, but controlling scales can be a challenge. Although there are some controls which can be used after the "armor" has materialized, it is important to identify and begin when the pest is in its nymphal stages or as a flying male adult. These controls include:
1) In the nymphal stage, the release of lady beetle larvae like the Mealybug Destroyer (Cryptolaemus montrouzieri), Chilocorus baileyii, C. circumdatus, Harmonia axyridis, or Lidorus lophanthae; the release of Green Lacewing larvae (Chrysoperla carnea); predatory Midges (Feltiella sp.); the release of Euseius sp. predatory mites; or a combination of the latter two;
2) In the adult stage, the release of parasitic miniature wasps like Aphytis melinus, Metaphycus zebratus, and M. helvolus; or a parasitic mite from the Cunaxoides sp.;
3) The use of pheromone traps to capture males;
4) Sticky traps to catch the flying males;
5) Insect growth regulators (IGRs) like fenoxycarb or methoprene to attack the "crawlers";
6) Or a plethora of various synthetic and organic pesticide controls.
Next time, we will take a look at two more rose-sucking pests: Whiteflies and mealybugs.
Note: Entomology information contained within this series is distilled from numerous on-line and text sources including those of Cornell, Florida State, Kentucky, North Carolina State, Oregon State, and Texas A&M universities; the Bio-Integral Resource Center, Berkeley, CA; U.S. Dept. of Agriculture; and Agriculture Canada. Additional reference materials from Insects of North America (McGavin; Longmeadow Press: Stamford, CT; 1993); Common Sense Pest Control (Olkowski, Daar, and Olkowski; Taunton Press: Newtown, CT; 1991); The IPM Practitioner (William Quarles, ed.; BIRC: Berkeley, CA); and Simon & Schulster's Guide to Insects (Arnett and Jacques; Simon & Schulster, Inc.: New York; 1981)
Rose Garden is just one of the 31 different
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