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. 

Saturday, May 14, 2016

Climate Change and Violent Tornadoes

Climate change induced by human activities apparently leads to many conditions that affect people and the natural world negatively. Negative aspects of climate change dominate the media, and understandably so, as some negative outcomes are likely to be painful. Many activists emphasize the negative aspects because they might lead people to take greater action. Yet, informed people should realize that not everything gets worse. Recently, Bill Nye tweeted "More severe weather. More suffering. Let's all take climate change seriously."  I strongly agree with the need to take climate change seriously. Yet, his focus on severe weather may be backwards!  During the tornado season, we all see the pictures, and they seem to create the feeling that this year is always worse than last. Yet, how do violent tornado outbreaks really trend over time? Data posted at the National Climatic Data Center website gives us clues:

Although F1+ tornadoes do not show much trend over time,

F3+ tornadoes actually show a pronounced and statistically significant downward trend (trend line not shown). Keep in mind that the way we observe tornadoes has changed over time. We are likely to identify more tornadoes given today's technology than we did in the past. The most intense tornadoes, however, are the most likely to have been observed and recorded, and they seem to be declining with time.

Study of the effects of climate change on severe weather is a young field. One major problem is that climate models do not simulate severe weather, so it is difficult to perform experiments to diagnose the causes of changes over time. Regional models embedded in climate models might be helpful. In any case, we can suggest hypotheses that might explain these changes. One possibility, for example is that climate change might reduce the size of temperature differences between cold Arctic and warm tropical air masses that meet over the plains of the United States that favor violent tornadoes. Tornadoes rely on the wind blowing from different directions at different heights, a condition that can be reduced if these temperature differences weaken over time.

My bottom line is that there are plenty of good reasons to take action on climate change. Yet, we should be honest and not claim that one of those reasons is to reduce violent tornado activity. Given the data, it would be astonishing if climate change were actually increasing activity in these severe storms.

****After posting this commentary, after some communication with experts in tornado data, I now understand that prior to 1977, intensity of tornadoes was biased to higher values relative to estimates of intensity of more recent tornadoes. This adjustment eliminates the downward long-term trend. At the same time, this change does not seem to suggest a trend upward, suggesting that it remains inappropriate to claim that violent tornadoes become more active with climate change.

Sunday, May 8, 2016

Spring Plastic Removal Day, Organic Agriculture, Roundup, Mulch, and Worms

Yesterday I celebrated spring plastic removal day. Every fall, I wrap my house in a bubble by enclosing my 3/4 wrap-around porch in greenhouse plastic. It provides a sunroom for the winter and cuts down on our home heating costs. I usually take the plastic down around May 1. It feels liberating the next morning to look out on my orchard in the front yard, from inside the house, without the plastic distorting the view. I keep an orchard of about an acre, with blueberries, raspberries, elderberries, aronia berries, hardy kiwis, tart cherries, pawpaws, table and concord grapes, apples, pears, apricots, and peaches. The cherries, apples, pears, and pawpaws are in bloom right now, and the hardy kiwis and table grapes are beginning to leaf out. Warmth in early March encouraged the plants to start waking up early, and that warmth was followed by an unusual cold snow event that destroyed most of my peach blossom buds. Out of 7 peach trees, we might only have 2-3 peaches this year!  That's 4 years in a row with basically no peach crop. The Albany area is borderline for peach production, though climate change is gradually making it better. The peach buds start to winter kill around -15F. Last winter was Albany New York's warmest on record (blame a combination of El NiƱo and climate change), but it also included the coldest individual night in more than 10 years.

I planted my orchard in soil with insufficient potassium and phosphorus for healthy fruit production. The people who contoured the land 16 years ago neglected to collect and replace the topsoil, leading to depression of these nutrients. I have been working for years to build the soil back up. Soils with insufficient concentrations in potassium, phosphorus, and boron can increase plant sensitivity to winter damage. I am rebuilding the soil with a thick layer of composted wood chip mulch along with potassium sulfate and mono ammonium phosphate. My soil is now full of worms and teaming with life.

I manage my orchard with a combination of organic and conventional techniques. I choose my pest and fungus control methods based on what works and what has been shown to be safe, not based on urban (or rural) legends or an assumption that organic is always best. Some people are dogmatic against use of chemicals, as if the word "chemical" itself implies something dangerous. Modern chemicals, hybridization, and genetic modification demonstrably increase the productivity of agriculture and allow us to feed the modern world. Anyone who argues otherwise is ignoring the evidence in favor of dogmatism. I like to make my pest control decisions based on evidence. It is true that some types of pests are just nuisances. A hole in an apple can be a minor problem (unless you want to store the apple for several months, because the holes encourage rot). Yet, some insects can completely destroy a whole crop, and some fungal pests can kill plants, make the fruit unpalatable, or produce natural chemicals that are toxic to humans and other life. Those toxins might be natural, but so is rattlesnake poison.

I reclaimed my orchard area from a wild meadow that was full of noxious weeds. Roundup weed killer can be a gardner's best friend in preparing a landscape for planting, but once the orchard is growing, it is difficult to use Roundup without damaging the crop plants. Over the years I have used organic techniques to replace the need for Roundup weed control. These techniques include flaming seedling weeds with a propane burner and building up a thick layer of composted wood chip mulch.

I'm not opposed to wise use of Roundup, however. I have read some interesting studies that have been interpreted to suggest that it is allegedly dangerous to humans. These studies claim, for example, that Roundup caused the death of human liver or umbilical cells in a petri dish. The culprit ingredient is the adjuvant, or the substance that causes the chemical to stick to the leaves of plants.
These studies, along with the numerous websites that repeat their claims, neglected to report that this component of Roundup is the same compound that allows baby shampoo to produce suds!  This same compound can be derived naturally from coconuts and from fats obtained from meats. Related compounds are frequently applied in organic agriculture as insecticidal soaps because they disrupt cell membranes, leading to death of soft-bodied insects. It is thus no surprise that this compound kills human cells in a petri dish--it disrupts the lipid bilayers of human cell membranes in the same way that baby shampoo cuts grease. Yet, to suggest that this component of Roundup is dangerous to humans as applied in fields is patently ridiculous, given that those who eat coconuts ingest it without complaint. It is no more dangerous to you than baby shampoo. Although injecting fully concentrated baby shampoo into your blood might be deadly, coming into external contact with it is not harmful. I'm not claiming that all components of Roundup are definitely safe. My point is simply that many people who make specific claims that it is dangerous often rely on misleading information from studies that have not been completely honest about the context in which their studies imply that Roundup can cause harm to humans. The majority of people who believe the claims of anti-Roundup websites do so because the website views are consistent with their pre existing biases.

For the sake of those who might consider my future offer of fruit from my orchard, but who might be opposed to Roundup use, please rest assured that I don't spray it anywhere close to my grape vines and fruit trees, else it would kill them too.