Monday, May 30, 2016

My Orchard is My Summer Hobby Laboratory

With spring semester over, my work time focuses on research and publication of results. When I'm not playing with my kids on my personal time, I work in my orchard and grape vineyard. Most of the pictures I have posted in my earlier blogs were from the orchard, so I thought I would include a little discussion about it. I have enjoyed gardening since I was four or five years old--It made a nice laboratory for a young scientist. Now, it yields tasty fruit along with struggles, frustrations, and some victories. I gave up vegetables a few years ago in favor of fruits, which tend to be more valuable and much tastier than the ones from the store.

Eight years ago, I planted my first pawpaw trees. This is my first pollinated pawpaw!  Several fruit have set so far this year. One of my trees is a seedling, which makes it a bit of a gamble in the pawpaw world--named grafted varieties produce more reliably tasty fruit, but once in a while a seedling turns out to be a gem. I have never actually tasted a pawpaw. Pawpaws are the largest fruit native to the United States. Some wild or seedling pawpaws have been described as insipid, but many people describe good ones as tasting like banana-vanilla custard. Mine should ripen in the fall. Fingers crossed.

The oldest vines in my grape vineyard are maturing, and I'm expanding the vineyard with new vines. I grow concord and table grapes. My favorite table grape variety is Somerset:
Four year old Somerset seedless grape vine nearing bloom.

Second year Somerset seedless grape growing its trunk. I also grow seedless canadice, mars, and a new variety called ticked pink.

Grapes take a lot of work to get tasty fruit year after year. They need to be pruned back hard during the dormant season, and I also thin the fruit clusters and the flowers within the clusters near bloom time (I comb them out with a hairbrush). I treat the young fruit clusters with gibberellic acid, a natural plant growth hormone that can be extracted from kelp, to stretch the clusters and expand the berries. Seeds in seedy fruit produce similar hormones that cause the fruit to grow, but seedless varieties often need a little help. I also girdle the vines above the first shoots to force more sugar into the fruit, while still allowing sugar from the lowest shoots to get to the roots. I end up with large fruit that taste amazing.

Growing grapes in a humid climate is a constant battle against fungus and insects. I put up a temporary electric fence in August to keep out the varmints. I grow the vines through deep wood chip mulch so I don't need to worry much about weeds.

I mount the vines on an 8 foot high trellis, much higher than most commercial vineyards. Benefits of the high trellis include raising the buds above the coldest air layer, which resides right at the ground level on cold winter nights and in the spring. I have had buds close to the ground break in the spring and freeze on cold nights, while the buds high on the trellis are often unharmed. The high trellis also prevents the vines from dragging on the ground. 

I raise apple trees, including disease resistant varieties, liberty, freedom, sundance, enterprise, and Zestar. I favor disease resistant varieties because of a disease endemic to my neighborhood called cedar apple rust. It is caused by a fungus that lives one stage of its lifecycle in apple trees and the other stage in cedars.  

Getting great apples is a battle against nature. Besides pruning and thinning the apples, I fight insects and wildlife. This year, four of my best 8-year old apple trees were completely girdled by voles next to the soil level. Starving voles chew the bark off in the early spring, seeking the tasty and nutritious cambium layer just below the bark. I thought my trees were old enough to be immune, but I could not have been more wrong. I learned the hard way to protect all the trees with hardware cloth. My deep mulch, while apparently healthy for the trees, also makes a nice home for voles. The girdled trees have leafed out and bloomed. Most apple experts suggest that without treatment, the trees would not be able to get sugar from the leaves into the roots. The roots then gradually lose their stored sugar. After running out of sugar, they cannot pump water and nutrients up to the treetop, which then dies. So, without surgery, I might possibly get a final harvest before the trees die. Some apple growers girdle their trees on purpose in oder to force sugar into the fruit instead of the roots, but they keep the girdled section narrow so that it quickly heals over. Mine would not have healed on their own. 

The objective of my surgical technique is to establish a new pathway for the tree top to feed the roots. I tried some approaches that have never been reported in the apple literature (at least as far as I know). I pruned off some lower branches, pealed off the bark, and stapled it to cleaned sections of the girdled bark to bridge between the remaining bark above and the root cambium below, with "up" in the same direction as it was on the original branch. A month later, several sections of the stapled bark remain alive, and it is thickening, suggesting that a new conduit between the tree and the roots is being made. In addition to the bark grafts, I performed traditional bridge grafts. Bridge grafts are made from young branches that are spliced under living bark above and below the girdle. I tried it both with sticks collected from the tree above and with pencil-thick root segments collected from another tree (note the reddish colored graft on the right side of the trunk in the picture above). The use of a root segment is another experiment, as all the experts suggest using sticks collected from above ground.

One successful project this year (so far) is carmine jewel tart cherries. The bushes are 7 years old and about 8 feet tall. They are covered with green cherries: 

These bushes laugh off our Albany New York winters. The most difficult parts of raising these cherries include fighting off fungus and removing the pits from the ripe fruit. Fungus control involves cleanliness, such as removing rotting fruit and cutting out sick branches. It also involves spraying the dormant plants in the winter with copper sulfate to kill spores from the year before. I spray fungus control before and after rainy periods. Harvest is in early July.

Finally, my hardy kiwi is nearing bloom (here is a picture of the fruit from last year):
These fruits practically grow themselves, but I prune them back hard in the winter and tip the new growth in the summer so the vines don't wind around each other.