Unstable Big Space High Profile Short life Expensive Few Cultivars

When comparing vertical and horizontal resistance, it is useful to think in terms of stability, space, spectacle, durability, cost, and breeding output. Vertical resistance is unstable (see 10.6). It has a wide climatic adaptation and a vertically resistant cultivar can usually be cultivated over a very large area. In this sense, it is 'big space'. Its effects are also qualitative. It protects completely or not at all. It is very conspicuous, and it has a 'high profile'. But, being unstable resistance, it does not endure. In this sense, vertical resistance is 'short life'. Breeding for vertical resistance is also expensive, requiring teams of specialists in large institutes, and the total breeding output is small. For this reason, vertical resistance breeding is 'expensive' and it produces 'few cultivars'.

It will transpire that, in these respects, the properties of horizontal resistance are the exact converse, and they are 'stable, small space, low profile, long life, inexpensive, and many cultivars' (see 6.5).

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