Lawson cypress vs Serbian spruce

Its most serious problem is Phytophthora root and collar rot: Lawson cypress is among the most susceptible garden plants. The foliage slowly fades to dull grey-green and then brown and the plant usually dies; there is no cure, so avoid heavy, wet or waterlogged soil and do not replant where one has already died this way. Phytophthora lateralis, the specialist pathogen that devastates the species in North America, has also turned up in Western Europe in recent years. In the hot, dry summers of Central Europe it suffers from heat and dry air unless watered and goes bare inside, and in cold winters the sunny, windward side can scorch. Weakened plants may also be attacked by the juniper jewel beetle, whose larvae tunnel under the bark and make whole branches die suddenly. Shops sell almost only its dwarf or columnar cultivars, which stay a fraction of the size of the species: check the size of the cultivar you choose before you buy.

Its best-known problem is the so-called omorika dieback: needles turn brown from the shoot tips and drop. It is not an infection but a physiological disorder triggered by magnesium deficiency, chloride building up in the soil (road salt, for example), compacted soil and weather extremes; a magnesium feed instead of potassium-rich fertiliser, loose soil and even watering prevent it, and it should not be planted next to salted roads or paths. In the hot, dry summers of Central Europe spider mites can turn the needles dull and greyish brown, and the green spruce aphid can make the older, inner needles drop. On heavy, airless soil root and butt rot fungi (Heterobasidion, honey fungus) may attack. It is somewhat less tolerant of polluted air than its reputation suggests, and it suffers both in prolonged drought and in waterlogged ground.