Yes, it is.
ZEN means ALL, and NOH means AGRICULTURE.
So, ZEN-NOH is a short form of "All Japan Agricultural Cooperatives Association".
They forced displaying their name as a brand, when buying products in large quantities from the manufacturers of agricultural machine. My YM1300 is ZEN-NOH brand too, it is perfectly same to Yanmar brand's. The difference is only decals on the hood.
As a very few case, there is some special model which designed by their local demands.
And for your information,in Japan, the joint use of an agricultural machine was rare.
This is for agricultural work to concentrate within a very short period. Especially for weekend farmers.
Relatively big farmer of the big city suburbs parted with their machines.*
Since farmland changes to a residential section and the big machine became*unnecessary.
It is the same also in the United States, isn't it?