Some disadvantages attend the setting of mixed orchards of pears, and these must be weighed and overcome as far as possible. There are many current statements to the effect that all varieties, whether self-sterile or self-fertile, are more fruitful and produce better fruit with foreign pollen than with their own. To old pear-growers, this seems to be putting it rather strong, but the statements come from accurate experimenters and observers and should have consideration. Cross-pollination, be it remembered, is not a cure-all for failures to set fruit. Unseasonable weather, lack of vitality in trees, various fungi, and no doubt other agencies, may be the cause of unfruitfulness. As to commercial varieties, the tale is soon told. Only a half-dozen sorts are generally planted in New York orchards. These, about in order of importance, are: Bartlett, Kieffer, Seckel, Beurré Bosc, Beurré d'Anjou, and Winter Nelis. To this short list may be added the following grown more or less for local markets: Clapp Favorite, Sheldon, Beurré Clairgeau, Lawrence, Howell, Tyson, and Mount Vernon. A list for the home orchard should include all of these and many more to be chosen from the major varieties described in Chapter IV. The pear flora of the country changes very slowly, and there are now almost no new sorts on general probation in the country. Perhaps with no other tree-fruits is it more important to begin with good trees, as even with the best it is often difficult to get a good start toward a pear-orchard. Black-heart, caused by winter-killing, is a sign that must be heeded, and a tree badly blackened in its pith, especially if the surrounding wood is discolored, should be discarded. Crown-gall on tap roots affects the tree deleteriously. Trees marked by hail or insects are often worthless. Other marks that commend or condemn trees are: A short stocky plant is better than a tall spindling one. A tree with many branches is better than one with few branches. The roots should be much branched rather than sparsely branched. A tree with smooth, bright bark is better than one with rough, dull bark. Both trunk and branches should be plump and show no signs of shrivelling. A poor pear-tree in the nursery seldom makes a good tree in the orchard. There is great variation in varieties as the trees come from the nursery, a fact to be considered. In New York, two-year-old trees are best.