It is nearly 20 years since I was appointed as a special ambassador for Toyonokuni kabosu, a kind of citrus fruit. (Toyonokuni is the old name of Oita Prefecture; it means “land of abundance.”) As an Oita-born resident of Tokyo, my job in this role is mainly to publicize the attractions of the prefecture. It is now the season of kabosu, but here, as part of my activities to trumpet the attractions of Oita, I would like to introduce another delicious specialty of the prefecture—shiitake mushrooms.
Why are Oita shiitake so tasty? The main reason is that only kunugi trees, a kind of oak, are used. This principle is instilled in growers through the shiitake cooperative and is strictly observed. Kunugi trees have thick bark, which is ideal for the reproduction of the shiitake bacillus. As a result, the harvested shiitake, the original produce of Oita Prefecture, turn out fleshy, tasty, and high quality.
Environmental preservation has entered the mainstream today, but for a long time a system of rotating shiitake cultivation in kunugi forests has been implemented in Oita Prefecture. After sprouting, kunugi trees are allowed to grow for 13-15 years before being pollarded for shiitake cultivation. This process is repeated in order from mountain to mountain, so the environment is protected as well. Furthermore, after growing for around 13 years, the trees are moved from the mountains to cultivation farms, which are sunny and slightly damp. This is the best environment for growing large, thick, and high-quality shiitake. Growers take it for granted that they have to wait patiently for a long time before the kunugi trees are ready. That is the essential point of Oita shiitake.
Around the time of the year when cherry trees blossom, spring shiitake are harvested. It is the largest harvest in the year, so the cultivation farms are very busy at this time. After spring, the farms have a quiet spell until the autumn harvest. For living things, the spring rains and the autumn rains are times of growth.
Perhaps the most famous type of Oita shiitake is the donko, which is harvested a little later from fall into winter. The chunky and delicious donko shiitake have a thickness of 2E centimeters and white cracks on their caps. They have established a firm reputation as the crème de la crème of Oita shiitake. They are also exported overseas, where they are extremely popular. In particular, donko shiitake are an essential ingredient in high-class Chinese cuisine.
Nowadays fossil fuels are used for drying, but in the past it was the custom to use charcoal. I can still remember that aesthetic ambience of smoke from the charcoal burning wafting through the mountains. Drying by charcoal was time-consuming, but I think the flavor was better.
Anyway, as someone who was involved in shiitake growing from childhood, I always feel delighted and proud whenever I see Oita shiitake being sold in Tokyo as genuine Oita produce. It was quite some time ago when, wondering why Oita shiitake were so popular even though other prefectures grew them as well, I investigated the matter. I happened to hear an Oita grower on TV saying, “It’s because we only use kunugi.ECome to think of it, yes, we did only use kunugi trees, and we took it for granted that the forests were rotated. I felt proud once again when I realized how marvelous this practice is from the environmental perspective as well.
Environmental concern was not limited to kunugi trees, either. Indeed, in the past it was common practice throughout Japan. For example, the methods of development recommended by the statesman Yanagisawa Yoshiyasu (1658-1714; the builder of the Rikugien garden) in Musashino on the outskirts of Edo (present-day Tokyo) were rational and very impressive indeed.