Lima bean

The lima bean (*Phaseolus lunatus*) goes by many common names, including butter bean, sieva bean, double bean, and Madagascar bean. This legume is cultivated for its edible seeds. Though they belong to the same species, culinary tradition sometimes distinguishes lima beans from butter beans: the former are typically small and green, while the latter are large and yellow. In places where both are called lima beans, the green variety is often labeled "baby" (or less commonly "junior") limas.

This plant originated in Meso- and South America. Two separate gene pools indicate that domestication happened independently in two regions. One lineage, the Mesoamerican type, spread through neotropical lowlands, while the other developed in the western Andes. The Andean domestication occurred around 2000 BC and produced a large-seeded variety (the lima type). The Mesoamerican domestication, around AD 800, gave rise to a small-seeded type (the Sieva type). By about 1300, cultivation had spread north of the Rio Grande, and by the 1500s, the plant was being grown in the Old World. The small-seeded Sieva type ranges from Mexico to Argentina, usually below 1,600 meters (5,200 feet) in elevation, while the large-seeded wild lima type is found in northern Peru between 320 and 2,030 meters (1,050 to 6,660 feet). The Moche culture (AD 1–800) heavily cultivated lima beans and often depicted them in their art. During the Spanish Viceroyalty of Peru, the beans were exported to the Americas and Europe; because shipping boxes were labeled "Lima, Peru," the beans got their name. In the United States, the term "butter bean" is widely used in North and South Carolina for a large, flat, yellow-white variety (*P. lunatus* var. *macrocarpus* or *P. limensis*). Sieva-type beans are traditionally called butter beans in the U.S., also known as Dixie or Henderson types. In the United Kingdom and the U.S., "butter beans" can refer to dried beans for rehydration or canned beans ready to use.

The lima bean is a domesticated species of economic and cultural importance worldwide, especially in Mexico. The species has two varieties: the wild form is *silvester*, and the domesticated one is *lunatus*.

In the United States, lima beans are a warm-season crop. They are grown mainly in Delaware and the mid-Atlantic region for processing, and in the Midwest and California for dry beans. Baby lima beans are planted in early June and harvested about ten to twelve weeks later. In western New York State, baby lima bean production increased significantly from 2011 to 2015.

In Oaxaca, Mexico, the main rainy season lasts from June to August, and most above-ground parts die during the dry season. Germination or budding occurs in June or July, with the first inflorescence in October or November. Flower and fruit production typically ends between February and April.

Both bush and pole (vine) cultivars exist. Pole types range from 1 to 5 meters (3 ft 3 in to 16 ft 5 in) in height. Bush cultivars mature earlier than pole cultivars. Pods can reach up to 15 cm (5.9 in) long. Mature seeds are 1 to 3 cm (0.39 to 1.18 in) long and oval to kidney-shaped. Most cultivars produce flat seeds, but "potato" cultivars have nearly spherical seeds. White seeds are common, but black, red, orange, and mottled seeds also occur. Immature seeds are uniformly green. Typical yields are 2,900 to 5,000 kg (6,400 to 11,000 lb) of seed and 3,000 to 8,000 kg (6,600 to 17,600 lb) of biomass per hectare. Bush types include 'Henderson' / 'Thorogreen' (65 days, heirloom), 'Eastland' (68 days), 'Jackson Wonder' (68 days, heirloom, brown seeds mottled with purple), 'Dixie Butterpea' (75 days, heirloom, with red speckled and white seeded strains), and 'Fordhook 242' (75 days, 1945 AAS winner). Pole types include 'Carolina Sieva' (75 days, heirloom; seed crop failures in 2011 and 2012 made this variety still hard to source ten years later), 'Christmas' / 'Chestnut' / 'Giant Speckled' / 'Speckled Calico' (78 days, heirloom, white seeds mottled with red), 'Big 6' / 'Big Mama' (80 days), 'Willow Leaf' (80 days, heirloom, with white-seeded and mottled strains), 'Mezcla' (82 days), and 'King of the Garden' (85 days, heirloom).

One pathogen of lima beans is *Phytophthora phaseoli*, an oomycete that causes downy mildew during cool, humid weather. Developing resistant cultivars is a cost-effective and environmentally safe way to combat this pathogen compared to using pesticides. Another disease, caused by *Didymella*, is a foliar problem in baby lima beans first reported in New York State. Symptoms include small, necrotic tan spots with red to reddish-brown irregular margins that merge and eventually cover the entire leaf. Lesions appear about 3–4 weeks after planting and increase until considerable defoliation occurs. Lesions are usually seen on stems. Two pycnidial fungi found on leaves are *Didymella* sp. and *Boeremia exigua* var. *exigua*, which is pathogenic on baby lima beans and contributes to the foliar disease complex. Other fungal diseases with similar symptoms include *B. exigua* var. *exigua*, pod blight from *Diaporthe phaseolorum*, and leaf spots from *Phyllosticta* sp. and *Phoma subcircinata*. Two-spotted spider mites (*Tetranychus urticae*) lay eggs on lima bean leaves.