136 Principles of Plant Culture. 



These thick, rapidly-growing shr)ots, with remote leaves 

 and poorly- developed buds, growing from the main 

 branches of unthrifty fruit trees, are most common on 

 undrained, heavy soils. They rarely produce much fruit, 

 but tend to rob the bearing branches of light and nourish- 

 ment. They usually continue to grow late, and in severe 

 winters are often injured by cold. ^Yater-sprol^ts may 

 also result from over-pruning and from inj ury of the tree 

 by cold, but in the absence of these conditions they sug- 

 gest the need of drainage. 



225. Fruits and Vegetables often Crack from Excessive 

 Moisture, either through too much absorption by the 

 ■roots or t»y direct absorption through the skin. Crack- 

 ing is most frequent after heavy lains following drought. 

 Apples, tomatoes, melons, carrots, kohl-rabi, cabbage and 

 the potato tuber are subject to it. On wet soils, drainage 

 may largely remedy the evil. The selection of varieties 

 least subject to cracking is also helpful, especially in 

 melons and tomatoes which often crack in comparatively 

 dry weather. In these cases, the cracking is probably 

 due to an unequal maturing of the fruit which causes 

 certain parts to grow faster than others. The bursting 

 of cabbage heads is due to the excessive absorption of 

 water by the roots. To prevent it, we start the plants 

 by pulling on the stem sufficiently to break a part of the 

 roots. 



226. Knobby Potatoes are caused by a wet period fol- 

 lowing a drought dui'ing the ripening season. Parts of 

 the plant that are still alive, stimulated by abundant 

 water, resume growth. But since cell division is possi- 

 ble only in the parts containing protoplasm, the mature 



