Agriculture Reference
In-Depth Information
plants should be in a block (not in one long row); orient the patch parallel to the main direction of the
wind to help maximize pollination.
HARVEST
Corn is ready to harvest when the husk leaves are completely dry and seeds are hard. Har-
vest ears with their husks and stems. Then remove husk, cut back stem, and hang upside down indoors,
somewhere with good air circulation and below 86°F (30°C), to dry. They can also be dried outdoors,
under an eave, for example, but be sure that birds cannot access the seeds. Harvest all hand-pollinated
ears, even if you do not need that much seed, to maximize the passing on of genetic diversity. In gener-
al one can say that fewer kernels from many ears is better than many kernels from fewer ears. Inbreed-
ing depression shows up quickly in corn, which is avoided by having a diverse seed stock. Harvest
ears from the middle of the patch if you have used the wind to pollinate your corn. Seed from the
middle of the ears is normally better developed than seed from either end. If you do not have access to
a traditional corn sheller, rub two ears together to separate kernels from cobs.
SELECTION CHARACTERISTICS
It is not absolutely necessary to be strict about varietal purity. If it
interests you, you can experiment with crossing varieties intentionally or just let yourself be surprised
by each year's new crossings by foregoing the techniques just described, which are mainly important
for maintaining varieties of open-pollinated corn. Without hand pollination (and, to a small degree,
even with hand pollination), there is always the danger that genetics from hybrid or genetically modi-
fied varieties from nearby fields could make their way into open-pollinated varieties.
Exact selection criteria are highly dependent on the variety. Adaptation to local conditions (drought
tolerance, production of ripe seeds in your climate) is important to all varieties. Additional general se-
lection criteria:
• handsome, well-developed ears (well covered by husks)
• true-to-type kernels organized in a true-to-type way (e.g., double rows, single rows, offset)
• good-looking plant (many older varieties, from which seed was saved from too few plants, show in-
breeding depression in the form of stunted growth or poor tassel and/or ear development; remove
these plants before they flower)
Potential selection criteria for sweet corn:
• many (two or three) sweet, soft ears per plant
• good, sweet, typical corn flavor (taste one or two ears per plant, leave one ear to ripen, note which
plants were tastiest)
DISEASES AND PESTS
The most common fungal disease of corn is corn smut (
Ustilago maydis
), af-
fecting sweet corn in particular. It causes drastic deformations of the ears (fist- to softball-sized galls)
but can also afflict stalks and leaves. Blue-black spores develop inside the gall, which then spread and
can survive for several years. Remove infected plants, rotate crops, and grow future crops with wider
spacing in an area with better air circulation. Modern varieties from central Europe and the USA are
mostly resistant to corn smut, whereas in Central and South America, galls are considered a delicacy
and eaten. Ripe spores are also used medicinally like ergot. Smutted corn is also used by some farmers
as silage. Aphids like to attack smaller stands of corn; use standard organic aphid treatments. Finally,
