By Calvin Chong and Al W. McKeown, Department of Plant Agriculture, University of Guelph Division: Horticultural Research Institute of Ontario, Vineland Station and Simcoe

"For as long as I can remember, I have loved chestnut trees. But I have never found a garden centre that sells them. Where can I purchase one?" In a nutshell, this consumer's remark in a recent Toronto Star Home Section is what this article is all about.

Passion for nuts
If you know anything about nuts, the name Ernie Grimo probably rings a bell. If it doesn't, it should. Grimo goes nuts over growing nuts - and making a big success of it. Within Ontario's relatively small nut growing industry - an estimated 1200 ha currently planted by commercial and hobby growers - Grimo is perhaps one of the most knowledgeable and enthusiastic of the group.

     After 35 years as a teacher, Grimo has spent many years learning and working with nut crops, and waiting for the time - he has recently retired - when he can devote himself fully to his passion of growing nut crops. Due to the scarcity of technical information on nut crop culture in Ontario, this remarkable man has literally "invented" his own way of doing things when it comes to nut crops.

     He has spent years of meticulous observation, experimentation and record keeping of his "many favourite" types of nut crops. He talks about them and introduces each individual tree like a proud parent describing his children. Over the years, in fact, Grimo has introduced nut trees to children through a program involving visits to local schools.

     It all started years ago for Grimo when he was vice-president of the U.S. National Nut Growers Association, which was founded in 1911. He started a Canadian Chapter with 17 members, which later evolved into the Society of Ontario Nut Growers (SONG), consisting mostly of hobby enthusiasts. Recently, SONG merged with its commercial counterpart, the Commercial Association of Nut Growers of Ontario (CANGO) with a total membership of 300, resulting in a better use of their limited resources.

Adaptation
In Ontario, nut crops are reliably hardy to about zone 6, and are especially adaptable to areas near the Great Lakes, that is, within the so-called Carolinian life zone (an area located between the northern portion of Lake Huron and Lakes Erie and Ontario).

     Prior to 1984, nut crop research was part of the Ornamental Research Programme at the Horticultural Research Institute of Ontario (HRIO), Vineland. As part of Ontario's New Crops Development Program, nut crop research was initiated at HRIO, Simcoe, in 1994. Currently, several heart nut varieties are being evaluated. Trials in progress are developing better orchard management practices, including pruning and fertilizer practices, use of mulches to reduce weeds, and fumigation for controlling soil-borne pests. Heart nuts and chestnuts were first harvested in 1998. It is estimated that Ontario nut growers could earn $3000 per year per acre. Grimo's estimate is closer to $10,000 per year. "Nut crops provide a wide market and have lots of potential for Niagara where the climate (zone 7) is most advantageous for growing these crops."

     As a novel crop in the Niagara area, nuts attract a lot of attention. Many farm tours include a visit to his nut farm, Grimo's Nut Nursery, located on Lakeshore Road, Niagara-on-the-Lake, Ontario. The small, 14-acre farm includes three-and-a-half acres of nursery stock (mostly nuts) and many varieties of butternut hybrids, walnuts, hazelnuts, as well as filberts, 15 varieties of figs and a diversity of persimmons, some of which are hardy in this climate. Filberts have some potential for commercial production but there is a need for blight resistant types. Among his unique nut collection, Grimo has a tree of an old favourite variety, Foddomeyr, valued for its very large nuts.

Heart nut the favourite
Grimo's most favourite nut crop appears to be the heart nut. It is a crop waiting to be commercialized. It is very adaptable to Niagara-on-the-Lake's "gentle" climate, which is similar to that in Japan where heart nut probably originated and is a popular crop. It is also widely grown in China.

     Compared to English Walnut, which comprises about 50 per cent kernel, heart nut consists of about 35 per cent kernel. With heart nuts, Grimo typically gets yields of about 2 tons per acre - comparable to that obtained in California - and up to 3 tons per acre with older trees. Younger (10-year-old) trees yield 1 ton per acre. To be viable commercially, a tree should yield about 75 lbs. each season.

     In the United States, heart nut sells for about $.75 U.S. per lb. When the heart nut is used in gourmet cooking, it can be sold for $2 to $2.50 per lb. in the shell. After cracking, nuts can be sold for about $7 per lb.

     Even the shells have value. Shells are typically ground to various size grades and used in the manufacture of polishing compounds. Oil well drill­ers use ground up shells to facilitate drilling in mud. Gourmet cooks use them in BBQ to flavour meats. Because of the heart-shape, heart nuts dipped in chocolate or placed on top of cakes could perhaps be sold in specialized markets as value-added confectionaries and baked products for Valentine sales.

Culture
Most heart nuts have a long dormancy period, and therefore, can be planted in June after being over wintered in a cold barn at temperatures near 0°. They are fast growers - with vigour similar to that of poplars reaching 8 ft. tall per year - and will produce a light crop after four years. Trees typically require spacing of about 40 x 40 ft. (about 27 trees per acre). Initially, trees are planted 20 ft. apart within the row. After 10 years, every other one is dug and transplanted at wider spacing. In one row of heart nuts, the trees at Grimo's farm were crowding each other after 11 years at a 32 ft. spacing.

     Large spreading branches are essential for subtending shorter current season shoots from which clusters of nuts are born. Rapidly growing branches, however, are easily subjected to breakage from wind and snow. Grimo typically fertilizes his trees once per year. More often would result in too much top growth. He propagates his nursery stock usually by shoot laying, grafting (cleft usually) and chip budding. Typically, he grafts selected varieties to seedling heart nut rootstock or walnuts and butternut hybrids. Newly grafted vigorous branches are kept upright by tying them to wooden supports attached to the tree. Supports are removed when branches are about 1.5 inches in diameter. He recently top worked five acres of walnut to new, more productive and desirable varieties.

Harvesting and processing
At Grimo's Nut Nursery, fresh heart nuts, sweet chestnuts, hazelnuts and Persian walnuts are available during harvest, which runs from the end of August to late October. Typically, the nuts are harvested after they have fallen to the ground or after trees haven been shaken mechanically. Grimo proudly displayed several types of machines used to pick up the nuts. The design is similar to that for machines used to pick up golf balls. Chestnuts, because of their shape, are the hardest for the machine to pick up. He has tried placing tarps under the tree but this is too labour intensive for most types of nuts. He, however, does this for hazelnuts.

     There were other pieces of machinery, some of which he designed or adapted for weakening or cracking the shells. One particular machine is capable of cracking up to 500 lbs. per hour. The biggest problem Grimo encountered in processing was finding the right machine that would orient the nuts the right way to ensure easy and consistent cracking of the wide assortment of nuts, each with a different size and shape. Also, after cracking, a sorter capable of separating darkened (usually bad) and light coloured (good) nuts would be desirable.

Bright future
In 1997, Grimo harvested the biggest bumper crop of heart nuts - 700 lbs. While this quantity is insufficient to the growing demands of his gourmet customers, he knows that the future ahead looks bright. Demands for his young nut nursery stock have increased from across Canada. As Grimo researches and tests for new desirable nut varieties - there continues to be little research or nut crops throughout the world - he faces diverse challenges and needs varieties that yield a higher proportion of kernel with thin shells that crack easier; varieties that are resistant to diseases such as canker (a fungal disease reportedly very lethal in Europe and elsewhere) and bacterial blight (a dreaded disease in California and present in Ontario); annual bearing butternuts (Grimo has no such variety as most are biennial bearers); and varieties that are more hardy to our climate. Availability of a wider selection of dwarf varieties would result in an increasing market for nut nursery stock. These would especially be more suitable for home and garden use.

     Grimo is confident some of the trees that are still within the 10-year observational period will become suitable for commercial use. In the meantime, he has a number of varieties that per­forms well enough at this time.

Selected references
Fleming, R.A., 1973. Nut trees for shade and food. Ontario Ministry of Agriculture and Food. AGDEX 240/18.
Gordon, J.H. 1993. Nut growing Ontario style. Society of Ontario Nut Growers, RR 3, Niagara-on-the-Lake, Ontario L0S 1J0. 172 pp.
McKeown, A.W. and C.J. Bakker. 1999. Edible tree nuts: Progress report. University of Guelph, Dept. Plant Agriculture, Horticultural Research Institute of Ontario, Simcoe, Ontario. 10 pp.
Ontario Ministry of Agriculture and Food. 1989. Nut culture in Ontario. Queen's Printer for Ontario, Toronto. Publication 494.
Ontario Ministry of Natural Resources and The Eastern Chapter of The Society of Ontario Nut Growers (SONG). 1995. Planting and caring for nut trees. Queen's Printer for Ontario, Toronto. AGDEX 334/343.