The Science of Pruning

Transcription

1 The Science f Pruning 610-1

2 Pruning Reference CMG GardenNtes available at #610 Pruning: References, Class Objectives, and Review Questins #611 Tree Grwth and Decay #612 Pruning Cuts #613 Structural Training f Yung Shade Trees #614 Structural Training Summary (2 page) #615 Pruning Mature Shade Trees #616 Pruning Flwering Shrubs #617 Pruning Evergreens #618 Pruning: Hmewrk Bks (available frm the Internatinal Sciety f Arbriculture at An Illustrated Guide t Pruning, Third Editin. Edward F Gilman. Cengage Learning Best Management Practices: Tree Pruning. Edward F Gilman and Sharn J. Lilly. Internatinal Sciety f Arbriculture ANSI A300 Pruning Standards, Part 1. American Natinal Standards Institute Bks (available frm Urban Tree Fundatin at Structural Pruning, A Guide fr the Green Industry. Dr. Edward F Gilman, Brian Kempf, Nelda Matheny, and Dr, Jim Clark. Urban Tree Fundatin Web: fr sample pruning specificatins. Pruning curriculum develped by David Whiting (retired), Alisn O Cnnr, and Eric Hammnd, Clrad State Univeristy Extensin Clrad Master Gardener training is made pssible, in part, by a grant the Clrad Garden Shw, Inc. Clrad State University, U.S. Department f Agriculture and Clrad cunties cperating. Extensin prgrams are available t all withut discriminatin. Cpyright Clrad State University Extensin. All Rights Reserved. Revised Octber

3 Learning Objectives At the end f this unit, the student will be able t: Explain hw trees grw and decay, and the implicatins fr pruning. Explain remval cuts, reductin cuts and heading cuts. Structurally prune a yung shade tree. Describe pruning f maturing shade trees, including bjectives (whys) and methds (hws). Prune flwering shrubs Prune evergreen shrubs Review Questins Tree Grwth and Decay 1. What is the branch cllar? a. Explain hw it develps. b. Explain the size relatinship between the side branch and trunk/parent branch necessary fr a branch cllar t develp. 2. Explain hw trees grw, adding xylem rings each year. Define the fllwing terms: a. Phlem b. Xylem c. Sapwd d. Heartwd e. Ray cells f. Cmpartmentalizatin 3. Explain hw trees respnd t wunds (i.e., CODIT). a. What are the rles f annual grwth rings and ray cells? b. In CODIT, explain why trees decay with a pipe-like structure. Hw des a break in the pipe-like structure impact structural strength? 4. What is percent shell? What are significant abut 33% and 25% shells? 5. Describe methds t evaluate decay and cracking in trees. Pruning Cuts 6. Identify/define the fllwing: a. Branch bark ridge b. Branch defense zne c. Reactin zne d. Wundwd 7. What is a remval cut? a. What are the advantages f a remval cut? b. When the branch bark ridge is visible, where is the remval cut made? c. If the branch cllar is nt easy t identify, where is the remval cut made? d. If the branch has n branch cllar, where is the remval cut made? e. What happens when the branch cllar is cut r injured? f. What happens when nubs r very shrt branches are left? g. With hindsight, hw des ne evaluate when the thinning cut was prperly made? 8. What is a reductin cut? a. What are the uses and limitatins f reductin cuts? b. What is the prper angle fr a reductin cut? c. In a reductin cut, what is the prper size relatinship f the branch being remved t the branch pruned back t? is it imprtant? 9. What is a heading cut? a. Hw des it influence regrwth f the plant? b. What are the effects f using heading cuts n larger branches? 10. Explain the three-step methd fr pruning large branches. Why is it needed? When is it needed? 11. Describe the prs and cns f pruning live branches during the: a. Late winter (drmant) b. Spring (during grwth flush) c. Midsummer (after leaves harden and turn dark green) d. Late summer and fall e. Late fall and early winter f. During drught 610-3

4 Structural Training f Yung Shade Trees 12. In structural training f yung shade trees, give the rule-f-thumb fr dsage (i.e., the maximum amunt f live wd/fliage remved per seasn)? Hw des the gardener determine the grwth rates t set dsage? Hw is the dsage range adjusted fr the specific tree? 13. Define excurrent and decurrent grwth habits. 14. List the steps and pruning bjectives fr excurrent and decurrent trees. 15. Define cdminant trunks. Why d arbrists have zer tlerance fr cdminant trunks? 16. What are the ptins if multiple leaders develp? If the main leader is killed? 17. What is the standard height fr the lwest permanent branch f sidewalk trees? Street tree? Trees in frest areas (fire management)? 18. What is the prper size relatinship between the trunk and side branch? Why is it imprtant? What are the ptins if a side branch is grwing t large? 19. Define scaffld branch. What is the rule f thumb fr minimum spacing f scaffld branches? 20. Hw d multiple branches arising at ne site influence the branch cllar and thus structural integrity? 21. What is the rle f temprary branches n yung trees? 22. Describe the management f temprary branches. 23. Given a yung excurrent r decurrent tree (r a picture f a yung excurrent tree), describe specific training fr this tree. 24. When decurrent trees are nt trained frm early grwth in the nursery and n the landscape site, it is ften impssible t fully achieve the five training bjectives. T minimize ptential strm damage, what is the mst imprtant bjective t pursue? Pruning Mature Trees 25. List the bjectives (whys) fr pruning a mature tree. 26. List the methds (hws) f pruning t achieve purpses. 27. Describe key elements in writing specificatins fr general pruning f maturing trees. 28. What is the verall bjective in structural pruning f medium-aged and mature trees? Why will it generally require wrk ver a perid f years? Hw des larger branch size influence the ptential fr structural pruning? 29. Describe subrdinate pruning. What factrs shuld be cnsidered when deciding where t make a subrdinate pruning cut? 30. Describe hw t subrdinate prune a mediumaged tree with the fllwing situatins: a. Cdminant trunks b. Runded ff c. Chked-ut central leader d. T many upright-grwing branches 31. Describe key elements in writing specificatins fr structural pruning f medium-aged trees. 32. Define cleaning. In cleaning, hw much f the live wd shuld be remved? Why? 33. When is it imprtant t remve dead branches? At what size and height des dead branch remval becme an imprtant management issue? 34. When wundwd is grwing ut alng a dead branch, where is the final cut made? 35. Describe key elements in writing specificatins fr cleaning. 36. Describing thinning. a. What are the purpses f thinning the crwn? b. Will thinning lwer a tree s height? c. In thinning the crwn, what types f cuts are made? d. What is the general maximum size f branches t be remved? 610-4

5 e. What is the lng-term effectiveness in verall crwn thinning t reduce strm damage ptential? What pruning methd wuld be mre effective? 37. What is lin-tailing? Hw des it differ frm thinning the crwn? What are the prblems assciated with lin-tailing? 38. What is the rule f thumb n dealing with excessive sucker grwth? 39. Describe the key elements in writing specificatins fr thinning. 40. In raising, what is live crwn rati? What is the rule f thumb n hw fast a tree can be pruned up? 41. In raising, what ptins may be wrkable ther than remval f lwer branches? Why may remval f lwer branches cause prblems? 42. Describe the key elements in writing specificatins fr crwn raising. 43. Describe the reasns fr crwn reductin. Describe the limitatins f crwn reductin. 44. List pinters n crwn reductin, as given in chapter. 45. What is the lng-term effectiveness in verall crwn reductin t reduce strm damage ptential? What pruning methd wuld be mre effective? 46. Hw des tpping a tree impact its structural integrity and internal decay ptential? 47. Describe the key elements in writing specificatins fr crwn reductin. 48. Explain the pruning bjectives fr the fllwing situatins: a. Strm-damaged trees b. Old and declining trees c. Rt-damaged trees d. Hazard trees Flwering Shrubs 49. What s the difference in flwering habit and pruning f spring-flwering shrubs and summerflwering shrubs? 50. Many gardeners prune flwering shrubs by tpping them. Describe the impact n grwth and flwering. 51. Explain the prs f, and limitatins fr, shrub pruning by a. Shearing t shape b. Thinning ld wd c. Pruning t the grund d. Replacement 52. What types f shrubs are successfully renewed by pruning t the grund? List situatins where this apprach may nt wrk. Evergreens 53. Hw can a gardener make a yung spruce, fir r Duglas-fir bushier? What abut a pine? 54. A large evergreen tree is vergrwing the space. Explain ptins t prune back the bttm branches fr spruce, fir and Duglas-fir. Explain ptins fr pruning back bttm branches fr pine. Why is pine different frm spruce, fir and Duglas-fir? 55. Explain what happens when a gardener shears a mug pine shrub. 56. On junipers and arbrvitae, explain the prs and cns f a. Shearing b. Thinning 57. Explain the prblems assciated with trying t prune back a severely vergrwn juniper r arbrvitae