¹Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108.
²Departments of Agronomy and Soil Science, Cooperative Extension Service and College of Agricultural and Life Sciences, University of Wisconsin, Madison, WI 53706.
November, 1989.

I. History:

The adzuki bean (Vigna angularis) has been grown and used for many centuries in the Orient. It was introduced to Japan from China about 1000 years ago and it is now the sixth largest crop and is a frequent subject in Japanese scientific publications. It is a cultigen not found in the wild and its center of origin is unknown but variously proposed to be China, India or Japan. Erect plant types are currently grown in northern provinces of Japan while the branching, vining types are cultivated in China, Manchuria and other warmer climate areas.

The major part of the Chinese crop is produced in the Yangtse River Valley. It also grows in south China, Korea, New Zealand, India, Taiwan, Thailand, and the Philippines. Its principal use throughout the Far East is as a confectionery item. It is cooked and combined with varying proportions of sugar, water, starch, plant gums, and other ingredients, and consumed as such or in combination with other foods. The single largest use of these so-called "ann" products is as fillings for bread (ann-pan), steamed breads or dumplings and sweet cakes. At least 50 other beans and legumes are also used to make these pastes, but the adzuki bean is the most prized, in large part due to its desirable red color, but also due to a delicate flavor and to the character-istic grainy texture of the pastes made from it.

II. Uses:

This crop is consumed directly as food, with little processing. Therefore, quality is important. Dark red color and a general plump, healthy appearance of seeds are the quality factors a buyer considers.

III. Growth Habits:

Adzuki bean is a legume. It germinates by epicotyl growth, leaving the cotyledons below the soil surface. They have an indeterminate growth habit which results in completely mature pods (1/8" diameter by 5" long), brownish in color, along with slightly yellow and completely green pods on each plant. Plants generally mature in 110 to 120 days after planting and are 18-25 inches tall.

IV. Environment Requirements:

A. Climate:

Adzuki bean has similar climatic requirements to soybean or drybean.

B. Soil:

Soil requirements for adzuki bean are similar to that of drybeans.

C. Seed Preparation and Germination:

Seed treatments for fungi, insects and bacteria are recommended.

V. Cultural Practices:

A. Seedbed Preparation:

A well prepared seedbed is advantageous to provide good soil to seed contact which aid in germination.

B. Seeding Date:

Adzukis are very slow to emerge, especially if the soils are cool (50^o-55^oF). Seedlings emerge in about 10-14 days when planted in late May. Earlier planted adzukis may take up to 20 days to emerge. Adzukis planted between May 11 and June 7 have yielded well at several Minnesota locations.

C. Method and Rate of Seeding:

Seeding rate should achieve 6 plants per foot of row in 30-inch row spacings. This seeding rate will achieve a plant population of approximately 105,000 plants per acre, (which is comparable to navy bean recommendations) and will require approximately 30 pounds of seed (25-35 pounds). Because of seed size and germination rate differences, growers should calculate rates based on their seed lot. Proper planting depth (1 1/2"), moist soil, and good seed-soil contact are required for uniform stands.

D. Fertility and Lime Requirements:

Legumes require neutral to alkaline soil for maximum N fixation by nodule bacteria. Soils with pH 5.8 to 6.4 have been used for adzuki production with few problems. Soils should be tested and, if necessary, limed to at least pH 6.0. Dolomitic limestone would need to be applied at least one year prior to adzuki production. Soils need to have medium to high soil test levels of P and K to ensure adequate fertility levels for maximum crop yield. In Wisconsin, these soil test levels are 31 to 60 lbs per acre and 221 to 300 lb K per acre depending on subsoil category. If necessary, soils should be amended with P₂O₅ and/or K₂O prior to seeding based on soil test results.

Maintenance phosphorus and potassium requirements are very similar to other edible beans (i.e. navy) and fertilizer equivalent to crop nutrient removal should be applied annually in order to maintain adequate soil test levels. Table 1 lists the maintenance P₂O₅ and K₂O necessary for grain yields ranging from 10 to 40 bu per acre. Some nitrogen is necessary to ensure good nodulation even though adzukis are legumes that have the ability to fix nitrogen if proper inoculation (Inoculant EL, Nitragin Company, Milwaukee, WI 53209) has been applied to the seed prior to planting. Table 1 also gives recommended N rates based on both crop yield and soil organic matter content.

Table 1. Maintenance N, P₂O₅ and K₂O recommendations for adzukis.
	Nitrogen Soil Organic Matter (T/A)
Grain Yield	<21	21-35	36-75	>75	Phosphate	Potash
bu/A	----------------------- lb N/A --------------------				lb P₂O₅ /A	lb K₂O/A
10-20	20	10	10	5	15	20
21-30	30	20	10	5	20	30
31-40	40	30	10	10	30	60

E. Variety Selection:

The most widely grown variety in the Upper Midwest is a Japanese import, "Takara" which was brought in from Japan in 1978. The variety "Minoka", a large-seeded adzuki bean, was released by the Minnesota Agricultural Experiment Station in 1980 but has not been widely grown.

F. Weed Control:

Adzuki beans are poor competitors against weeds because of early slow growth, so a combination of chemicals and cultivation are required.

1. Mechanical: Select fields with relatively light weed pressure to grow adzuki beans. Rotary hoe 7 to 10 days after planting to kill the first flush of weeds as they emerge. This should give a sufficient height difference between weeds and the crop to effectively use row cultivation. Delay the first cultivation until the primary leaves are fully developed. Cultivate a second time 10 to 20 days later, if needed.

2. Chemical: Treflan (3/4 - 1.0 qt/A) alone or in combination with Amiben (1 gal/A) as a preplant incorporated treatment has given the most consistent weed control. Amiben can also be applied alone as a preemergence treatment. Basagran (3/4 pt/A) is an approved broadleaf herbicide for postemergence use. Many of the other herbicides used on edible beans should not be used on adzuki beans.

G. Diseases and Their Control:

White mold (Sclerotinia sp.) and a bacterial stem rot Pseudomonas adzukicola) have been problems in adzuki bean production fields in the past.

To help prevent problems with these and other diseases in adzukis a good rotation program (small grains and/or corn), use of disease-free seed, and a spray program should be implemented.

H. Insects and Other Predators and Their Control:

No information available.

I. Harvesting:

Adzukis mature later than some other edible beans. About 118 days is a typical maturity period, depending upon the growing season. Mid-September is a typical harvest date.

The indeterminant growth habit of the plant means that there will be completely mature pods (1/8" diameter by 5" long), brownish in color, along with slightly yellow and completely green pods on each plant. The stems may be slightly green with several green upper leaves present.

Some growers pull and windrow adzukis early in the morning to allow drydown, followed by combining later in the day. Others have direct combined the beans with grain headers or used row crop headers.

Shattering of pods is common, so care is needed to prevent large harvest losses. Selection of harvest maturity is also important. Delaying harvest until late in the season or late in the day will likely increase harvest losses. Slower speeds and opening the concaves to avoid splitting beans and damaging the seed is also necessary. The pods shatter very easily to release the seeds.

VI. Yield Potential and Performance Results:

Research plot yields of adzuki bean in Minnesota have ranged from 0 to 4,000 lb/a and averaged about l400 lb/a. Yields have been the highest on the lighter soils under irrigation. The management required to produce good yields are similar to that used for other edible beans.

VII. Economics of Production and Markets:

Adzuki markets are limited and acreage is contracted in advance of planting. Quantity use of adzuki products are presently limited, but new markets are being developed domestically and overseas.

VIII. Information Sources:

Adzuki Bean Cultural Information. 1987. L. L. Hardman. University of Minnesota Extension Service, St. Paul, MN.

Varietal Trials of Farm Crops. 1988. Report No. AD-MR-1953, Univ. of Minnesota Agric. Exp. Sta., St. Paul, MN.

References to pesticide products in this publication are for your convenience and are not an endorsement of one product over other similar products. You are responsible for using pesticides according to the manufacturer's current label directions. Follow directions exactly to protect the environment and people from pesticide exposure. Failure to do so violates the law.