CORN (FIELD & SWEET)

Transcription

1 1. Varieties Field Corn: Sweet Corn: Seed rate: 2. Seed Treatment (FIELD & SWEET) Pioneer Hybrids, Local selections Renat Hybrid, Sugarburst 5-10 lbs per acre (depending on seed size) Commercially available seed is usually pre-treated to protect against insects and fungi. Locally produced seed can be treated with a malathion + captan dust. 3. Spacing and Planting Seeds may be planted mechanically in rows 30 to 40 inches apart with seeds 6 to 9 inches apart in the row. Mechanical planting can be done using a Stanhay Seed Drill or a cotton/corn planter. Since seed size is very variable in corn varieties, the hole-size in the seed belt or seed plate has to be selected accordingly. By hand, holes can be made 12 inches apart along the row, placing 2 seeds in each hole. 4. Seasonality Corn may be planted throughout the year with irrigation. Under rain-fed conditions it is safe if planted during August and September, since yield is positively influenced by soil moisture availability at tasseling. 5. Duration of Crop This varies with variety, but is approximately 3 months to harvest for roasting and sweet corn. 6. Weed Control a) Pre-plant herbicides: If young annual weeds are present in the field apply 2 pints (950 ml)/acre of paraquat (Gramoxone Super, Millquat, Herbiquat). For hard to kill annual weeds e.g. whitehead bush (Parthenium sp.), wild poinsettia (Euphorbia spp), apply a mixture of paraquat and diquat (Reglone) at rates of 2 pints (950 ml) per acre for both. For hard to kill annual and perennial weeds apply either glyphosate (Roundup, Wopro-glyf) or sulfosate (Touchdown) at recommended label rates. b) Pre-emergence herbicides: Apply pendimethalin (Prowl 42.3 EC) at 3 1/3 pints (1575 ml)/acre. OR Metolachlor (Dual 960 EC) at 1 1/4 pints (570 ml) per acre. OR Alachlor (Lasso 4E) at 5 pints (2365 ml) per acre. c) Post-emergence herbicides:

2 i) Broadleaf weeds only. Apply either 2,4-D amine 6S at 2/3 pints (315 ml) per acre when most weeds have germinated. Spray after corn emerges and until it is 5-8 inches tall. May cause corn to become brittle - do not cultivate for about 2 weeks after application. Drop nozzles or hand-held knapsack sprayers may be used to apply 2,4-D as a directed spray, missing the leaves after corn is 10 inches tall, and until 2 weeks before tasseling. Avoid spray drift to susceptible crops. Some sweet corn varieties are sensitive to 2,4-D. OR Apply dicamba (Banvel 4S) at 1/4 to 1/2 pint ( ml) per acre from early post emergence and up until corn is inches tall. Not recommended for use on sweet corn because of crop injury. ii) 7. Insect Control SUCKING: Aphids Young annual grasses and broadleaf weeds. Apply 2 pints (950 mls) per acre of paraquat (Gramoxone Super, Millquat, Herbiquat) using directed spray, missing the stems and leaves of plants. ALWAYS READ THE PESTICIDE LABEL PEST* PESTICIDE* DTH* COMMENTS* BITING/CHEWING: Cutworms Malathion OR 7 Diazinon OR 7 Dimethoate OR 14 Perfekthion Lambdacyhalothrin Karate 3 OR Azadirachtin 3 Neem-X Diazinon OR 7 Pirimiphos-ethly Primicid Apply diazinon or Primicid soon after planting; or use a synthetic pyrethroid e.g. permethrin, cypermethrin, as soon as damage first becomes apparent. Army worms Azadirachtin OR 0 Neem-X Bacillus Dipel, Agree, New Bt, Xentari thuringiensis OR 0 Carbaryl OR 1 Sevin Permethrin OR 1 Ambush Cypermethrin OR 5 Sherpa Deltamethrin OR 1 Decis Lufenuron 20 Match Corn Earworms Carbaryl OR 1 Sevin Cypermethrin OR 5 Sherpa Permethrin OR 1 Ambush Deltamethrin OR 1 Decis Lufenuron 20 Match Spray silks twice weekly for 2-3 weeks.

3 NOTES ON PEST CONTROL * For application rates of pesticides - check directions for use on the pesticide label. Also consult pesticide suppliers and/or the Extension Section of the Ministry of Agriculture. * DTH = the minimum number of Days to Harvest from the last pesticide application. Where no information is given please consult the pesticide supplier. Always use pesticides with short DTH approaching or during harvest. * The synthetic pyrethroids available are permethrin (Ambush), cypermethrin (Sherpa), deltamethrin (Decis), and lambdacyhalothrin (Karate). * IGR = Insect Growth Regulator. These products mainly control larvae and nymphs, but seldom adults. Examples of IGR's available are buprofezin (Applaud), Chlorfluazuron (Jupiter), flufenoxuron (Cascade), cyromazine (Trigard), Azadirachtin (Neem-X), and lufenuron (Match). * Check plants carefully at least twice weekly for pests. Sucking pests are usually found on the underside of the leaves. * For control of a particular pest, use one of the listed pesticides per application, and rotate with others as needed in the spray programme. * The best times to spray are in the morning between 7.00 a.m. and a.m. and in the late afternoon after 5.00 p.m., when: a) Few insects are on-the-wing and bees are not active, b) The sun is not strong enough to scorch plants, c) Foliage is dry, and d) Wind speeds are low. * The best way to spray is to wet thoroughly the stems, buds and undersides as well as the tops of leaves. * Always use a wetter-spreader-sticker (e.g. Citowett) at recommended rates with the spray solution. It binds the chemical to the plant thus negating the effect of the rain, and wind. * It's advisable to use a complete foliar fertilizer (e.g. Bayfolan, Nutrex, Novafol) in the spray solution to help improve the quality of the water, and provide some of the nutritional needs of the crop. The quality of the water refers to its freedom from extraneous materials such as dirt, etc., and also the ph (acidity or alkalinity) of the water. The ph of the water is adjusted by addition of special adjuvants (e.g. ph Plus, Indicate 5), where necessary. Check with the Extension Staff of the Ministry of Agriculture for more information on these areas. * Combination of pesticides to be tank-mixed for the first time should be checked for compatibility before use. Incompatibility negates the efficacy of pesticides in the spray solution, and can result in plant injury - phytotoxicity. Some information on physical compatibility can be obtained by mixing small quantities of the pesticide materials in a separate container in the correct proportions. The combination should be tested on a small scale to determine safety to plants before proceeding to full field-scale usage. Further information on compatibility can be obtained from compatibility charts, consulting with pesticide suppliers, and the Ministry of Agriculture.

4 * Keep spray solutions agitated to prevent settling-out of wettable powders and flowables; and avoid leaving spray solution standing in tanks for extended periods e.g. overnight. 8. Disease Control ALWAYS READ THE PESTICIDE LABEL DISEASE* PESTICIDE* COMMENTS Corn Smut (Ustilago maydis) Stalk Rots (Various fungi) Leaf Spots (Various fungi) See comments NOTES ON DISEASE CONTROL These corn diseases are of sporadic occurrence and of minor importance. * DAYS TO HARVEST (DTH) = the minimum number of days to harvest from the last pesticide application. Where no information is given, please consult the pesticide supplier. * Check plants carefully about twice weekly for diseases. For accurate disease identification and/or diagnosis, consult with the Extension Section of the Ministry of Agriculture. * For application rates of pesticides - check Directions for Use on the pesticide label. Also consult the pesticide supplier and/or the Extension Section of the Ministry of Agriculture. * See NOTES ON PEST CONTROL. 9. Fertilizers In the absence of an adequate and reliable soil testing service, the following recommendations are given as a guide for the direct application of NPK fertilizers to the soil. a) Basal dressing: during land preparation, apply in the bed and incorporate during rotavation the following fertilizers: - 3 x 50 kg bags of triple superphosphate, plus, 4 x 50 kg bags of Where fertilizer was not incorporated during land preparation apply 6 x 50 kg. bags of 12:12:17+2 or a similar mixed fertilizer per acre at planting. For large-scale corn production, planting is best done using cotton/corn planters with fertilizer drill attachments. Fertilizer drill attachments are adjusted to place the fertilizer to the side and below the level of the seed. Specially formulated fertilizers are required, since all types do not flow evenly in these fertilizer drill attachments. b) Side Dressing: at the pre-tasseling stage (about 6 weeks after planting) sidedress with sulphate of ammonia at 2 x 50 Kg bags per acre.

5 10. Harvesting Field corn for roasting: Harvesting should take place when the grain is at the "milk" stage. This occurs when the silks are drying and become brown, and the grain can be crushed with finger pressure. Field corn for milling: This should be delayed as long as practicable to allow for natural drying of the grain in the field. In unfavourable weather or where birds or other pests cause severe field damage to ripening corn, the crop may be harvested earlier, and dried artificially to 10 to 12% moisture content. Sweet Corn: May be harvested as "baby corn" where the entire cob is utilized, or later at the "milk" stage. 11. Yields Field corn for milling: Approximately lbs per acre of dried grain from the hybrid varieties and lbs per acre from local selections. Field corn for roasting, and Sweet Corn: Approximately lbs per acre rain-fed and lbs per acre with drip irrigation. DISCLAIMER: The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Ministry of Agriculture and Rural Development. Use pesticides safely. Read and follow label directions. Coordinating Editor : Henderson A. Williams Typists: Juel Hackett and M. Rose Bourne Graphics : Trevor Pollard Computer Editors : Samuel Inniss and Mark Byer