Gloomy Scale Diagnostic Guide
Gloomy scale (Melanaspis tenebricosa) is a pest of maples primarily in the Eastern US. It rarely kills trees, but can predispose them to other insects/fungi.
Trees at Risk
Gloomy scale attacks: red maple, silver maple, boxelder, catalpa, elm, hackberry, mulberry, and sycamore.
Signs of Damage
- Stunting and general dieback are the only symptoms.
- Bark is often dark with mold.
- Dark grey scale covers are most noticeable in August.
- Scales infest only twigs, branches and bark.
- In June/July nymphs are visible and will settle on bark and twigs.
- Eggs are laid in June/July.
- Crawlers emerge June/July/August (eggs hatch in 24-48 hours).
- Overwinter as mated females.
Gloomy scale is very difficult to manage after populations are established. Early detection is critical for best management of infested trees. Monitor three to four year old twigs for the gray protective covers of this armored scale insect. Heavily infested branches should be pruned and destroyed.
Soil Application using Transtect
Dosage: 1 pkt/5 in DBH Timing: Early spring is best for control later that year. Re-Treatment: Annually
Systemic Bark Spray using Transtect
Dosage: 6 - 12 pkt/1 gal water (1.5 – 2.0 oz/in DBH) Timing: Spring close to crawler emergence Re-Treatment: Annually
Foliar Spray using Transtect
Dosage: 1 pkt/25 gal water Timing: At crawler emergence beginning late May – early June. 8 weeks after full leaf expansion of red maple Re-Treatment: Crawlers emerge over a long period of time. 2-3 sprays may be required from initial activity through Sept
Foliar Spray using Distance
Dosage: 8 - 12 oz/100 gal water Timing: During summer apply Distance™ + RTSA Hort. Oil™ as crawlers emerge in June/July Re-Treatment: Reapply if additional crawlers are noted after 14 daysDistance$269.00
Foliar Spray using RTSA Horticultural Oil
Dosage: 0.5% - 1%/100 gal water Timing: During summer apply Distance™ + RTSA Hort. Oil™ as crawlers emerge in June/July Re-Treatment: Reapply if additional crawlers are noted after 14 daysRTSA Horticultural Oil$39.00
Foliar Spray using Up-Star Gold
Dosage: 1.7 oz/100 gal water Timing: Apply at crawler emergence in June/JulyUp-Star Gold$33.33
Spraying during crawler emergence is required for effective control. Improving the growing conditions and plant health will benefit stressed trees.
A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy forestryimages.org. Use of the images does not imply endorsement of treatments by forestryimages.org