Ellis, M. A. and DC. Ferree. 1981. How powdery mildew affects apple photosynthesis and transpiration. Ohio Report 66(5): 67-70.
Interdisciplinary research was initiated to determine the effects of powdery mildew infection on photosynthesis and transpiration in apple leaves. The results of this study demonstrate several important considerations in the development of such a model for powdery mildew in apple. Leaf age at the time of infection and timing of fungicide applications after infection appear to be important factors. When leaves are infected early in development, they will never attain their full photosynthetic capability. However, timely application of a fungicide to eradicate the fungus may allow development of new leaves. Leaves develop some form of resistance to powdery mildew as they mature. Therefore, the rate of infection and subsequent reduction in photosynthesis is greatly reduced with age. When mature leaves are infected, timely application of fungicide to eradicate the fungus appears to stop further reduction of photosynthesis and transpiration.
Preaus, Kenneth B. and C.E. Whitcomb. 1981. How does the digging method affect tree transplanting success? Am. Nurseryman 154(4): 9-10, 18-20.
Tree spade manufacturers make many claims about transplanting success with their machines. But few studies have been done to compare tree spades with conventional B&B techniques for survival rates and for costs per amount of time needed. To determine the merits of the various transplanting methods for trees, four digging and planting treatments were compared. Ball glazing from the tree spade is not as serious as was originally thought, at least when loose backfill can be placed in intimate contact with the face of the ball following transplanting. On the other hand, when a tree dug with a tree spade is placed in a hole dug by a tree spade, air spaces are likely to be left in numerous places around the ball. Removing enough soil from around the top of a hole dug with a tree spade to provide loose backfill down as far as the major roots in the ball dug with a tree spade may increase survival and growth. Digging machines can be used about as successfully as B&B techniques. The pull method deserves more attention, particularly for transplanting large trees.
- © 1982, International Society of Arboriculture. All rights reserved.
