For temporary control apply moss-killers. Lawn sands containing sulphate of ammonia and sulphate of iron will give good contact kill. A suitable formula is 3 parts sulphate of ammonia and 1 part calcined sulphate of iron mixed with 10 parts medium grade lime-free sand. Apply at 40Z per square yard(nog per m2) during fine weather, ideally on a moist, dewy morning with fine weather ahead. Subsequently irrigate the lawn if, after 48 hours, there has been no rain. Dichlorophen is an effective chemical moss-killer and is the active ingredient in some proprietary lawn moss-killers. It is applied as a spray to wet the moss thoroughly. When the moss is dead rake it out, then attend to whatever cultural factor initiated the infestation. LAWN PESTS Among the most troublesome are: 1. Leatherjackets (Tipula spp.). These are the larvae of the crane fly, hatching from eggs laid in late summer to feed on grass roots during autumn and winter. Damage shows the following summer as patches of yellow turf. Check for larvae by lifting a piece of turf and forking underneath, or soak a patch of lawn and cover overnight with sacking to bring grubs to the surface, To control, water with HCH in late September-October or in mild, humid conditions late March-April. 2. Chafer grubs (Phyllopertha horticola). These have creamy-white curved bodies, brown heads and three pairs of legs. They feed on grass roots, emerging in late May or June as large brown beetles to lay eggs and continue the cycle. To control, dust with HCH in late May or June. 3. Earthworms (Allolobothora spp.). These eat only decaying organic matter, not grass roots, but their surface casts are unsightly and encourage weeds if flattened by the mower. Scatter casts as they are drying, when they crumble readily. They are most troublesome in the autumn and early spring and are encouraged by liming and by leaving mowings uncollected. If troublesome, they can be controlled by watering the turf with chlordane as worms are becoming active. They are killed underground, the treatment being effective for about a year. LAWN DISEASES The two most troublesome diseases are fusarium patch disease and corticium disease or red thread. 1. Fusarium patch disease (Micronectriella nivalis, syn. Fusarium nivalis). This disease is also called snow mould and usually occurs in spring or autumn during mild, damp weather, showing as small, irregular, yellow patches which eventually turn brown and die but often grow larger and coalesce before doing so. In damp weather snow-like white or pinkish fungus forms around the patches. Attacks are more likely where turf is compacted or has received nitrogen-rich dressings in late summer. To control mild attacks and check more serious attacks water with a solution of ioz sulphate of iron in \ gallon of water per square yard (7g in 2.5I of water, per m2). To control heavy attacks apply fungicides containing quintozene, benomyl, thiobendazole or thiophanate-methyl, according to manufacturer's instructions.