SERVICE Appearance of fungal diseases in the calendar year* *When conditions are favourable for the fungus, they can also appear at times other than these! Animal pests Animal pests include insect larvae, snails, moles and mice that eat the roots, leaves and stalks, dig up piles of soil and dig out holes and tunnels. When insect larvae are present in large numbers, they can eat through roots and destroy plant parts above ground, creating considerable damage. Voles and field mice can be controlled by using traps or chemical means. Insect larvae and caterpillars Some of the best-known and most common insect pests are those in the Tipula genus, also known as crane flies. The adult crane flies have long legs, thin bodies and narrow, translucent wings. The crane fly larvae are present especially in periods of wet weather in late summer and autumn as well as in areas with damp and mild-winter climates. They feed off underground shoots and leaves. The little crane fly larvae overwinter in their juvenile stage of development. When they are grown, they reach a length of around 40 mm. Their main feeding time is April to May. Symptoms of an infestation are the grass looking limp, the lawn gradually turning straw-yellow, dying off and leaving behind bald patches. Signs of a heavy infestation might be flocks of crows or starlings searching for food on the lawns and pecking at the sod. Other insect larvae that can cause damage to lawns are wireworms (click beetle larvae), cockchafer grubs (May beetle, June beetle and garden chafer larvae), cutworms (larvae of various moths) and mosquito larvae. In particular, the larvae of the March fly (Bibio hortulanus), which live in large colonies or nests, can cause widespread damage under the surface of the lawn. They eat the roots and other plant parts just under or above the ground. This leaves a thin, loose grass cover that is unsightly and susceptible to dryness. It can be lifted up and rolled like a rug. The flies can produce two generations in a year. They like to settle in particular in lawns that are not used and walked on very much. Name Botanical name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Snow mould Microdochium nivale x x x x x x x Grey snow mould Typhula incarnata x x x x x Leaf blight Drechslera-, Cuvularia spp. x x x x x x Red thread Laetisaria fuciformis x x x x x x x x x Ophiobulus Gaeumannomyces graminis x x x x x x x Dollar spot Sclerotinia homoeocarpa x x x x x Root rot Phytium ultimum x x x x Rust Puccinia spp. x x x x Fairy rings Marasmius oreades x x x x x x x x x x x Puccinia spp. – Rust SYMPTOMS Various types of rust (brown, yellow, black rust) cause restricted growth. Pustules in various shapes and colours form on the leaves. Rust appears especially on Poa species. TREATMENT Good supply of potassium, sufficient moisture and fast drying, as well as a not-too-short cut in summer in dry weather can have preventative effect. Pythium spp. – Root rot SYMPTOMS The root crown is black and chocked; dead patches with green leaves; at first, white mycelium, later a grey slimy mass. TREATMENT Since wet soil and cool temperatures promote the development of fungi, aeration and sanding as well as appropriate watering and a balanced supply of nutrients help prevent root rot. Gaeumannomyces graminis (Ophiobolus) Stem canker SYMPTOMS Small, depressed spots of 50 mm to 100 mm in diameter, with a pallid or bronze-like colour. Later, expansion of the spots and dying off of the affected grasses (mostly with Agrostis). TREATMENT Avoid heavy liming and unbalanced supply of nutrients; no fungicide currently approved by the authorities. Laetisaria fuciforme (Corticium) Red thread SYMPTOMS Formation of fine pinkish mycelium spots during wet periods; leaf sheaths stick together; later needle-like, forked, coral-red fibres; Festuca rubra is most susceptible. TREATMENT Improve supply of nutrients; in particular, nitrogen fertiliser in combination with lime and phosphates. Good soil aeration and a not-too-short cut can prevent spreading. 68
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