hello, my name is mike parker, and i’m thetree fruit extension specialist at north carolina state university. today we’re at the researchorchard at the mountain horticultural crops research station in mills river. today we’dlike to discuss apple rootstocks and their performance in north carolina. the orchardwe are in today is a gala orchard and is part of the nc 140 regional rootstock researchproject. the nc 140 is a group of my colleagues
aapl stock value, from across the country. we evaluate rootstockson a wide range of multiple locations, multiple varieties and multiple systems. apple trees are budded or grafted onto applerootstocks. as you know, apple trees, when planted from seed, do not come true. whenwe plant an orchard, we want the orchard to
be of a specific variety. so in addition tohaving trees that come true to seed and true to variety, we also select rootstocks basedupon their ability to tolerate the climate, whether it be cold or heat. we also selectrootstocks that are tolerant to insects and diseases that are of specific concern in theenvironment they are being planted. the major issue we look at apple rootstocksis also for size control. do you want to have trees that are very large, take a long timeto come into bearing? or would you be looking at size controlling rootstocks or dwarfingrootstocks, where all the work can be done from the ground and they are highly efficientrootstocks? the tree i am sitting next to right now isan m7. it’s a large semi-dwarfing apple
rootstock, and as you can notice, the workneeds to be done from ladders, which can be time consuming, and can also result in issueswith worker safety. today i’d like to talk about several of the rootstocks we are lookingat in north carolina, that are very promising and have commercial potential. when looking at apple rootstocks, you’llnotice that there is a letter followed by a number. those letters may be m or mm – mallingor malling-merton, coming from england. there is also a series of rootstocks coming fromrussia. they are called budagovsky, bud or just abbreviated to b. there is also a seriesof rootstocks abbreviated cg or g. that is referring to geneva. this is a series of rootstocksthat were developed at cornell in new york.
the rootstock we are standing next to nowis a bud 9. bud 9s produce a tree that is approximately 35 to 40% of a full size tree.it is utilized primarily because of its field resistance to fire blight bacteria. in northcarolina, the size of a bud 9 is seriously affected by the amount of the rootstock shankthat we leave out of the ground. the greater the length of the rootstock out of the ground,the greater the dwarfing will be. as we said, bud 9 is used because of its field resistanceto the fire blight bacterium. conversely, if we look at a rootstock that is used primarily– the m 26 – it is very susceptible to fire blight bacterium. this tree was lostlast year because of fire blight infection. the rootstock we are standing next to nowis m 9 nakbt 337 – or just abbreviated m
9 337. this rootstock is the primary rootstockplanted in the united states. it is a dwarfing rootstock. the characteristics – we havea tree here that goes up to a supported height of 8 feet – our stake, you can see, goesup to 8 feet. the ultimate height of this tree will be held to approximately 10 feetin this orchard. another selection of m 9 is called m 9 pajam2. this is an m 9 pajam 2 here. it is a more vigorous tree than the m 9 337. you can noticethat by the fullness of the canopy that it fills in. but both the m 9 and the m 9 337rootstocks provide growth control that results in a tree that’s approximately 30 to 35percent of a full size tree. another promising rootstock in our evaluationsis g 41. g 41 produces a tree approximately
the size of an m 9. it is very resistant tofire blight. it is also tolerant to re-plant disorders. another rootstock in our evaluations is g11. g 11 produces a tree approximately the size of an m 9. it is resistant to fire blight,however it is not resistant to re-plant disorders. another promising rootstock in our dwarfingevaluations is g 16. g 16 is resistant to fire blight and is partially tolerant to re-plantdisorders. one of the most promising rootstocks in ourdwarf evaluations is a g 935. g 935 produces a tree that is a little smaller than an m26. it performs very well in re-plant sites. it’s also very resistant to fire blight.it is also very precocious, or bears fruit
very early. in most of our research trials,g 935 has been the most productive rootstock after the fourth year. one of the largest dwarfing rootstocks thatwe are evaluating is m 26. m 26 produces a tree that is approximately 55 to 60 percentof a full sized tree. one of the shortcomings to m 26 is its susceptibility to fire blight.especially when we are planting fire blight sensitive varieties such as fuji or pink lady,which make m26 not the best choice in those situations. another promising rootstock in our evaluationsfor the semi-dwarf trees is a g 30. a g 30 produces a tree approximately 65 percent ofa full sized tree. g 30 performs very well
in replant sites. however there are some nurseryproduction issues at this point in time that may limit its availability. another semi-dwarfing rootstock is a g 210.g 210 produces a tree that is approximately 60 to 65 percent of a full sized tree. itis also very resistant to fire blight and to re-plant disorders. when we are evaluating semi-dwarf rootstocks,many growers still prefer m 7 rootstocks because they do not require an extensive support system.in north carolina, m 7 is the most pre-dominant semi-dwarfing rootstock planted. however,we have found in replant sites it performs very poorly, and is not recommended in thosesituations. this is an m 7 tree. we plant
those in an approximately 10 by 20 foot spacewithin the orchard. we do not expect significant production until at least year 5. we’ve just looked at 9 year old gala trees,and the rootstock performance up until this point in time. however, this is ongoing research,and behind me you’ll see a planting of 4 year old aztec fujis. this is also part ofthe nc 140 project, and its planted across the country. this is ongoing research at thecollege of agriculture and life sciences at north carolina state university. the goalof this research is to help the growers of north carolina to be profitable and productive,and sustainable in their orchard operations. for more information on apple rootstock thatmay be suitable to your site, visit the e-extension
site and look for apple rootstocks. we developedthe e-extension site from the research based information generated from the nc 140 regionalresearch group. this information is provided to assist all of the apple growers in theunited states to help their operations to be much more productive and profitable.
