Leaves, Stems Wither And Collapse - Normal Aging
As the summer progresses sweet woodruff plants tend to grow leggy and rangy. They naturally collapse of their own weight, their foliage withering and browning except at the tips of the stems. Among the common sweet woodruff problems, this natural aging process is frequently observed. Plants that lack moisture and/or are in sunny locations tend to do this earlier in the season. Locate sweet woodruff in the shade and keep the soil moist. Try cutting back plants that are showing signs of withering to encourage new growth.
Ragged Holes In Leaves - Slugs
Slugs are essentially snails without protective shells. They are typically 1 to 2 inches long and either white, gray, yellow, or brownish black. Slugs are attracted to moist, well-mulched gardens and acidic soil. They are active at night, rasping holes with their file-like tongues in leaf and stem surfaces. They often leave a telltale trail of silvery mucous behind as they travel. They hide under boards or leaf litter during the day. Control them with a trap made from a shallow plate baited with beer set in the garden bed. The slugs are attracted to the yeast in the beer, climb in, and drown. Begin trapping the pests 3 to 4 weeks after the last frost.
For more information see file on Dealing with Slugs and Snails.
Pale Patches On Leaves - Downy Mildew
Downy mildews are caused by fungi that grow and spread on moist leaf and stem surfaces. These fungi form pale areas on upper leaf surfaces and gray or white or purplish "downy" patches on undersides. They are especially active in periods of cool wet nights and warm humid days, causing leaves to wilt and die. Plant sweet woodruff on well-drained, fertile soil; water in the morning.
Avoid crowding your plants. Try to keep their foliage dry by watering just the soil. Dig up out heavily infected plants together with any adjacent soil and discard them in the trash. Spray lightly infected plants with flowable sulfur or dust them with lime sulfur or Bordeaux mixture when downy mold first appears on leaf undersides. Several applications may be needed to achieve control. While mildew will probably not kill the plants, it will make them unsightly, defeating their value as attractive ground cover.
For more information see file on Dealing with Fungal Disease.
Leaves Spotted Or Blotched - Fungal Leaf Spots
Many kinds of leaf spots are caused by fungi that thrive on moist leaf surfaces and cause transparent to brown or black spots that disfigure the leaves. Some fungal spots are surrounded by flecks or black dots, their spore-bearing fruiting bodies. Often spots come together to form larger patches of dead tissue.
Pick off and discard any infected leaves on sweet woodruff. Remove any dead plant debris promptly from the yard to reduce overwintering spore populations. Dig out and discard seriously infected plants together with the soil round the roots. Mulching helps prevent splash-borne infection in outdoor plantings. Spray at weekly to 10 day intervals with wettable sulfur or Bordeaux mixture, particularly in wet weather. (Watch for leaf discoloration with the latter.)
For more information see file on Dealing with Fungal Disease.
Orangish Powdery Spots On Leaves - Rust
Rust diseases caused by various fungi produce pale yellow areas on upper leaf surfaces and orangish powdery spots of fruiting bodies on undersides directly beneath. Infected sweet woodruff stems and flowers may be seriously deformed. Remove any infected leaves as soon as possible. Remove and destroy all garden debris before plants start to grow in the spring. Control weeds in and around the garden. Control insect pests which help spread rust with insectidical soap. Prevent rusts with periodic sprays of wettable sulfur on vulnerable plants, starting several weeks before the disease normally appears. Space plants widely apart for good ventilation, and avoid wetting the foliage when watering.
