They resemble commercial pintos in most characteristics. They are less viny and about 2 weeks earlier in maturity than the old Colorado strain, but are slightly more viny and a little later in maturity than the Idaho and Wyoming strains. Their seed-coat pattern is practically identical with that of the commercial varieties, except that it is somewhat brighter and has a clearer white background and darker brown markings. The new pintos require approximately 96 days to reach maturity, a few days later than the Idaho and Wyoming Pintos, but about 10 days to 2 weeks earlier than the Colorado strain. Thus in many western areas they can be threshed before other row crops, like sugar beets, are harvested.

Like the Idaho and Wyoming commercial strains, Pinto No. 5 and No. 14 are primarily adapted to irrigation. Under dry-land conditions they may not yield quite so well as the Colorado strain, which is primarily a dry-land type, but No. 5 and No. 14 are fairly well adapted to those conditions, and dry-land farmers may want to grow them in preference to the Colorado strain because they mature earlier.

When we started the breeding work we realized that we would need several years to produce a rust-resistant pinto. Besides, rust was becoming a serious menace to the Great Northern beans in Wyoming and Montana, and no variety or strain resisted the disease. So it seemed desirable to devise chemical spraying or dusting methods of control. We tried many different chemicals, both sprays and dusts, with success; but in cost, ease of obtaining materials, and efficiency, sulfur dust appeared to give the best results under field conditions in Colorado.

Bean rust overwinters as resistant black spores which germinate in the spring about the time the beans are planted. Each spore produces four smaller spores, which are spread by the wind and may infect the young bean plants. If a smaller spore lights on a bean plant, and conditions are right, it germinates and grows into the leaf. In about 10 days, small white flecks appear on the under side of the leaf ; soon they break through the leaf surface, and the rust spots or pustules appear. Each pustule contains hundreds of a third kind of spore, the brown summer spores, the ones that farmers first notice. They also are blown about by the wind and spread infection to other beans. Each single spore may produce another rust spot with hundreds of spores. If the humidity is high enough, from either rain or dew or irrigation, the rust fungus produces a crop of spores in 10 days from first infection. Unless something is done to control the disease, a severe epidemic may occur.

Tests under field conditions in Colorado have proved that when sulfur is applied to beans fairly early in the season, before rust spots become visible, the control is excellent. The sulfur destroys the comparatively few rust pustules that are present at that time. The secondary spread from these spots is stopped and the formation of other infection centers is prevented. If dusting is done after the rust is rather advanced and widespread throughout the field, more applications of sulfur dust are needed and the control is not so complete. If rust is widespread in an area, two or three dustings are usually necessary, even though the first one was applied early in the season, because spores from undusted fields may later be blown to fields that were dusted. Since sulfur is effective for only about 10 days, another application is necessary if viable rust spores are present.

The ideal time to dust is when the atmosphere is quiet and the plantings are not wet with rain or dew. The sulfur should be applied at the rate of 20 to 25 pounds to the acre. If two dustings are made, 15 pounds can be applied the first time, when the plants are small, and approximately 20 pounds at the second dusting. Naturally, care should be exercised in getting as good a coverage as possible.

In parts of Colorado the Mexican bean beetle (Epilachna varivestis Muls.) is frequently a serious pest. Entomologists have found that basic Copper arsenate controls this insect in Colorado and does not injure beans. A mixture of 25-percent basic copper arsenate and 75-percent sulfur dusted on beans at the rate of 20 to 25 pounds to the acre is recommended to control both rust and the Mexican bean beetle at the same time.