Sugarcane rust which is of interest because no vertical resistance occurs against it (although a few cases have been falsely reported). This is because sugarcane is derived from a continuous wild pathosystem. The disease has occasionally been damaging when it appeared in an area of susceptible cane, as happened recently in Cuba. In general, however, the disease is quite unimportant, as it has been completely and permanently controlled with horizontal resistance. Puccinia graminis tritici
Stem rust of wheat. There are three rusts of wheat, the others being yellow rust (Puccinia striiformis) and leaf rust (Puccinia recondita). Stem rust has probably attracted more research than any other plant disease and, sadly, virtually all of it has been associated with vertical resistance. There is now great scope for work with horizontal resistance and this is within the capacity for amateur breeders who are willing to tackle some of the more technical aspects of plant breeding.
Stem rust is a heteroecious parasite, and its winter host is the barberry (Berberis spp). It has long been known that wheat that was growing near barberry bushes was more quickly and more severely diseased with rust. In Britain, it proved possible to eradicate all the barberries and stem rust is no longer a serious problem. However, the eradication of barberry in larger areas, such as North America, presented insuperable difficulties. Puccinia hordei
Rust of barley. It seems that all breeding for resistance to this disease has involved vertical resistance and there is much scope for work with horizontal resistance. Puccinia polysora
The tropical rust of maize which was accidentally taken to Africa some four centuries after maize itself. This was consequently a re-encounter disease and, at low altitudes near the equator, it was extremely damaging. Attempts to breed for vertical resistance proved futile and, in the course of some 1015 maize generations (i.e., 5-7 years) the disease declined to unimportance, as a result of a natural accumulation of horizontal resistance. This phenomenon has been largely ignored by most plant pathologists but it is, in fact, one of the most important plant pathological events of the twentieth century, as it has taught us exactly how to breed for horizontal resistance. There is a full account Return to Resistance, available as shareware at this website. Puccinia purpurea
Rust of sorghum. This is generally an unimportant disease because sorghum is open-pollinated, and it responds to selection pressures for horizontal resistance during cultivation. Puccinia recondita
Leaf rust of wheat and rye. On rye, this disease is unimportant because rye is open-pollinated and, because it responds to selection pressures during cultivation, it has adequate horizontal resistance. On wheat, however, it is an important disease, mainly because all breeding during the twentieth century has involved vertical resistance. Amateur breeders working with wheat should definitely aim at horizontal resistance to this disease. Puccinia sorghi
The common rust of maize. Unlike Puccinia polysora, which has epidemiological competence only in the lowland tropics, the common rust occurs wherever maize is cultivated. It is rarely important because most maize cultivars have adequate horizontal resistance to it, because they are open-pollinated and can respond to selection pressures during cultivation. Puccinia striiformis
Yellow or stripe rust of wheat. This rust also attacks barley, and rye. As a general rule, stem rust is a serious disease in the warmer wheat areas, while stripe rust is serious in the cooler areas. They are rarely both serious in one area. amateur breeders working with wheat should consequently be concerned about one or the other but not both. And they should pay strict attention to on-site selection. Pulses
Crops of the family Leguminoseae in which the harvestable product is the seed, otherwise known as grain legumes. Includes various categories of beans, peas, lentils, and grams. Pumpkin
See: Cucurbita pepo. Punica granatum
The pomegranite, a native of Iran but well known to the ancient Romans.
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