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Corn

Scientific name: Zea mays
Family: Poaceae

Growth stages 

 

Pests 

For weeds and diseases please see further down on this page. For rodents, snails and slugs please click here 

Seed

 
Sown seeds  Ants
Seedcorn maggot
White grub
Wireworm

Seedling Stage

 
Roots  Root knot nematode
Seedcorn maggot
White grub
Wireworm
Stem   Cutworm
Leaves   Corn flea beetle
Corn leafhopper
Corn stalk borer
Cutworm
Rice/Corn seedling maggot

Vegetative Stage

 
Stems  Corn borer
Corn stalk borer
Leaves  Aphids
Armyworm
Corn borer
Corn stalk borer
Locusts

Reproductive Stage

 
Silk  Corn borer
Corn earworm
Japanese beetle
Spider mites
Tassel  Corn borer
Corn earworm
Spider mites
Corn ear   Corn borer
Corn earworm
Corn stalk borer
Grain   Corn borer
Corn earworm
Corn stalk borer
Smut

Maturation stage

 
Corn ear   Corn borer
Corn earworm
Grain   Corn borer
Corn earworm

Weeds

Grasses
Sedges
Broadleaf

Diseases

Fungal
Bacterial
Viral

Agro-ecology

Intercropping corn with beans and other legumes regulates pests (leafhopper, leaf beetles, stalk borer, and fall armyworm) and increases the land utility. Intercropping Canavalia (Canavalia spp.) with corn improves soil productivity. Sow Canavalia seeds 4 weeks after sowing corn. Place 1 seed/hole in a row between corn rows with 50 cm between holes. Allow Canavalia to grow after harvesting corn until it is time to plant the next crop. Then plow-under the plant materials into the soil (CIAT, 2000).

Intercropping corn with beans and squash enhances caterpillars' parasitism. This practice increases the abundance of natural enemies where food sources for beneficial insects are made available (Altiere; Nicholls, 2000). The intercropping system of corn-beans-squash is a low input and high yield strategy in the tropics. Corn yield is increased by as much as 50% over monoculture yield. Although the yields for beans and squash are reduced, the overall yield for the three combined crops is greater than when grown separately in monocultures (Agroecology Research Group, 1996).

Desmodium (Desmodium uncinatum) and Melinis grass (Melinis minutifolia) when planted in between corn rows keep the stem borer moths away. These plants produce chemicals that repel stem borer moths. Napier grass (Pennisetum purpureum) and Sudan grass (Sorghum vulgare sudanese) are good trap crops for corn from stem borer attack. Napier grass has its own defense mechanism against crop borers by producing a gum-like-substance inside its stem, this prevents larva from feeding and causing damage to the plant. Also, Sudan grass increases the efficiency of natural enemies when planted as border crops (Herren; Pickett, 2000).

Nitrogen (N) requirement of corn is 220 kg/ha for maximum yields. Any decrease in the rate of N fertilizer applied will reduce yields. This suggests that the usual N fertilizer recommendation is much below the optimum level. N should be applied as split applications, - either before or at planting. Depending upon the N leaching and the crop appearance, the remainder can be applied in one or two applications at about 40 days after germination (IFA, 2003). N deficiency results in a loosely filled cob, however, overuse of N should be avoided.

Many soils provide substantial amounts of the phosphorus (P) and potassium (K) but this is not adequate enough, especially at the seedling stage. Apply P near the seed for early seedling vigor. K is taken up in large quantities but plants' requirement can usually be estimated by soil analysis. K deficiency results in empty cob ends, while P deficiency results in hollow grains. However, fertilizer recommendations based on soil analysis provide the very best chance of getting the right amount of fertilizer without over or under fertilizing. Ask for assistance from a local agriculturist office.

In rainfed corn growing areas, plant seeds along with the first rain. This will allow roots to absorb the natural nitrates formed with bacterial action in the soil. Roots are susceptible to poor drainage which cause stunted and yellowing of leaves. Stagnant water results to loss in N through leaching and denitrification (FADINAP, 2000).

Further information

A perennial variety of teosinte (Zea diploperennis) a wild grass closely related to corn has been discovered in the mountains of the state of Jalisco in Mexico. The variety carries only 20 chromosomes similar to that of corn. It is hoped that when the plants are crossbred, the new hybrid will grow perennially and also have the ability to tolerate moist and even wet soils (UNESCO, 2000).

A study entitled "The use of sugar solutions to enhance the impact of predators of fall armyworm in maize" was conducted for a period of two years to apply artificial honeydews to corn crops to attract natural enemies in the field. Result showed that applications of sugar solution to maize increased the numbers of natural enemies which coincided with the decreases in fall armyworm damage and infestation rates (O'neil; Canas, 1996). The use of artificial honeydews by small scale farmers in the Tropics is an alternative to synthetic pesticides because of no risk of poisoning in application and storage, the ease in preparation, and the ready availability of sucrose sources, such as refined sugar and other sugarcane by-products.

OISAT Field Guides

Field Guide to Non- chemical Pest Management in Corn Production download (1149 kb)

External links


References


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