Integrated Pest Management For Corn

You might have just established your farm with numerous stands of corn (Zea mays), beautiful! As there is going to be great profit either commercially or for local consumption, but just as it is necessary to observe the daily routine maintenance of your maize farm land for maximum harvest, it’s also mandatory to implement IPM against those enemies of yours (pests, insects and diseases). IPM in corn is one of the techniques to control pests in a maize farm; it is the use of two or more pest control methods to eradicate or reduce the population of pests in a maize farm to achieve a cost-effecrtive result.

Let us go over this, you might want to ask me what IPM is, this is what it is: Integrated pest management (IPM) is a pest control strategy that combines two or more methods of pest control (either use of biological and cultural method or cultural method and chemical practices to control insect pests) to create a more effective force towards the control of pest in agricultural production. It aims to use several natural enemy or predators to control identified pests, using selective pesticides for backup only when pests are unable to be controlled by natural means. IPM has copious benefits for the farmers, society and the environment. IPM in corn farm offer farmers the best pest control strategy, good use of resources, opportunities to increase yields and profits, new technology and reduced potential for weed resistance.

Maize can be attacked by a wide range of insects pests. The primary pests of maize are the helicoverpa and a number of soil-borne insects. There are numerous disease, insect, and weed problems can influence the profitability of field corn production in New York. The most important pests of corn are seed corn maggots, cutworms, armyworm, European corn borer, western and northern corn rootworms, ear molds, foliage and stalk diseases, and weeds. Though, minor pests, like rodents, occur irregularly and may not be a problem every season. Integrated pest management (IPM) practices can be used to help minimize or avoid these pests damage.   

Primary Pests In Corn Farm And IPM Control Methods

#1. Corn Earworm (Helicoverpa armigera)

Corn earworm, Helicoverpa armigera, is major and common corn pest. The female moths lay and deposit eggs on the stem, leaves (both sides) tassels, silks and husks on the upper two-thirds of plants; the larvae developed on the silks or husks may cause significant damage. The eggs hatch to caterpillars usually before silking; this cause minor damage to the tassels but may cause major damage when migrating to cobs. The damage done to the Silk reduces pollination and grain-set. Similarly, the caterpillar feeds on the top of the cob, and may result in the presence of mycotoxins.

The damage on Leaf can indicate pest presence; parallel rows of holes seen on corn leaves are signs of feeding on unopened leaves. Usually, Corn Earworm are not considered economical to control, except in high value seed maize.  

IPM Control Strategy: Several pest control strategies can be used to control corn earworm. The use of insecticides (Chemical control) is targeted at small caterpillars (up to 5 mm); it must be applied directly at tassels and emerging silks. The best product to use in an integrated pest management system is a naturally occurring nucleopolyhedovirus (NPV). There are a number of commercially formulated NPV products on the market for the control of corn earworm. This is a biological control method.

The best cultural control method is seed selection; corn varieties with husks that extends 50-80 mm beyond the top of the cob and closing tightly around the silks restrict the entry of larvae into the cob. In addition, irrigating corn during dry weather prevents the husks from loosening.

#2. True wireworm larvae

This pest bore into germinating corn seed and chew on seedling roots and shoots resulting in reduced vigour, wilting or seedling death. Damage is worse when crop growth is retarded by dry, wet or cool conditions. Wireworms generally favour moist areas. True wireworm larvae may also feed on helicoverpa pupae.

IPM Control strategies: Cultural practice by using germinating seed baits or soil sampling test prior to planting to detect larvae prior to sowing. Also, close monitoring of crops after sowing until establishment to hunt for this pest. Other control methods are Seed dressings, in-furrow sprays and granular insecticides offer some control.

#3. False wireworm larvae

The false wireworm larvae is more aggressive during the spring; it attacks germinating seeds and seedling roots and shoots in spring, resulting in patchy stands. Damage is mostly found in early planted crops with low crop residue. Adult wireworm may damage summer seedlings by chewing at or above ground level and replanting may be required

IPM control strategies: Wireworm can be controlled through soil testing by using hand sifting 10 soil samples (30 x 30 cm) or placing 10 germinating seed baits throughout the paddock; a single larva per sample warrants control. This is a cultural control method. Other ways is through land preparation and planting; using press wheels at planting can destroy the pest habitat. Chemical control through seed treatments or in-furrow sprays can effectively control the larvae while adults can be effectively controlled using cracked grain baits.

Note: Infestations of wireworm detected after crop emergence cannot be controlled.

#4. Cutworm larvae

Cutworm is another primary maize pest that feed on leaves and stems of young plants. it cuts down plants to eat the leaves. Partial damage to stems may cause the plant to wilt. Larvae typically reside in the soil during the day and curl into a ´C´ shape when disturbed. Cutworms may be found in any type of soil and often move into the field from adjoining fence lines, pastures or weedy fallows. Damaged areas by cutworms tend to be patchy and the highest risk period is during summer and spring.

IPM control strategies: Cultural practice by regular Inspection of emerging seedlings twice per week. Chemical treatment of seedlings when there is a rapidly increasing area of infestation or high population resulting is over 10 percent loss of seedling. In addition, treat older plants if more than 90% of plants are infested or if more than 50% of plants have 75% or more leaf tissue loss. The application of insecticide to prevent caterpillars is also very helpful. Ensure fallows are kept clean and perimeter weeding of about 3 meters away must be kept. The application of herbicides to weeds can greatly influence the attack of cutworm as they are forced to move from weed hosts into the corn field.  

#5. Black field earwig

Black filed earwig is one of the major pests of maize of great economic importance. Earwig eats newly sown and germinating seed and the roots of crops resulting in loss of plant or poor establishment. Feeding on secondary roots of maize by black field earwig may cause the plants to fall over, as they get larger. Severe damage is usually observed in soils that retain moisture well, and earwigs prefer cultivated soils to undisturbed soil .

IPM control strategies: close monitoring of crops after planting to detect pest acivities. Conventional land preparation method to uncover and destroy pest prior to planting has been noticed to be very helpful. Use of germinating seed baits to confirm the presence of pest in the soil and control if more than 50 earwigs in 20 germinating seed baits.  Grain baits containing insecticide should be applied at sowing for better protection.  

#6. Armyworm

Armyworm is a subtle and deleterious pest, highly baleful at its larval stage. They are called armyworms because of their ability to invade a farm in large numbers. The armyworm moths lay their eggs in clusters of 25 or more under the lower leaves or at the base of the plants. The larva or caterpillar, the most destructive, is a small worm of about 1.5 inches.

They feed subtly on the leaves; they are not easily noticed. The larvae are about 1 – 1.5 inches long and live for just 3 weeks; they feed on mostly grasses and cereal crops with corn being their favorite. Armyworm larvae consume leaf tissue and at times, they chew the leaves of small cereals or grains. In severe cases, they may strip the leaf margin and move up to feed on the panicles and floral parts. Armyworm larvae also feed on plants’ flag leaves.

IPM control strategies: Offseason is the period at which these pests are inactive and dormant. Armyworm resides in grassy vegetation; they are more rampant when reduced tillage or zero tillage is adopted.  Conventional tillage practice eradicates all grasses and weeds on the field, leaving no room for armyworm moths to lay their eggs. Also, the soil is pulverized such that the moths are exposed to unfavorable condition, thus, expelling the moths and preventing them from laying eggs. Insects such as lacewing and ladybugs all feed on armyworm eggs as well as the newly hatched larvae. Trichogramma wasps also prey on armyworm; they parasitize any newly laid eggs by inserting their eggs inside the armyworm eggs, thus, killing the armyworm eggs before they hatch into larvae. Use neem oil, it is very effective on various stages of the armyworm growth. It repels pests greatly.

#7. Corn Aphids

Corn aphid is the most common aphid species on maize and can affect maize crop at any stage. Aphids are known for sucking into plants to consume the sap juice; the adults and nymphs suck sap and produce honeydew. High population of occurence can cause plants to turn yellow and appear unthrifty resulting in yield loss as a result of moisture stress.

IPM control strategies: Chemical control methods are generally not cost effective and the insecticides that control aphids may have negative impacts natural enemies. Regular Inspection to detect pest activities has been proven helpful. Biological control by the used of predators of aphids like ladybird larvae, damsel bugs, bigeyed bugs, larvae of green lacewings, Wasp parasitoids and larvae of hoverflies greatly help in corn aphids control

Components Of Integrated Pest Management

The components of Integrated pest management (IPM) include the biological, cultural and chemical practices to control insect pests; these series of activities helps to interfere with the conditions that makes pests thrive.

The Cultural practices

Cultural methods of pest control is a nonchemical method that involves the manipulation of farm conditions in such a way that either destroy the pests or prevent them from causing economic loss. Various examples of cultural practices that can be used to control pests are:

  • Removing plant debris, trimming of bunds, treating of soil and deep summer plowing which kills various stages of pests.
  • Testing of soil suitability for nutrients deficiencies on the basis of which fertilizers should be applied.
  • Selection of clean and certified seeds
  • Seed treatment with fungicide or bio-pesticides before sowing for seed borne disease control.
  • Selection of pest resistant/tolerant seed varieties which play a significant role in pest suppression.
  • Adjustment of time of sowing and harvesting to escape active period of pest attack.
  • Crop rotation non-host crops within the cycle.
  • Proper plant spacing of crops which makes plants more healthy and less susceptible to pests.
  • Optimum use of fertilizer; the use of farmyard manure and bio-fertilizers should be encouraged.
  • Proper water management as the high moisture content in soil for prolonged period is conducive for development of pests especially soil borne diseases.
  • Proper weed management.  weeds compete with the crops for micro nutrients also harbor many pests.
  • Setting up sticky traps for white flies and aphids
  • Growing trap crops on the borders or peripheries of fields
  • Inter-cropping or multiple cropping wherever possible. Not all crops are not preferred by each pest species; certain crops act as repellents.
  • Harvesting as close as to ground level. This is because certain developmental stages of insect pests/diseases remain on the plant parts which act as primary inoculum for the next crop season. Hence, harvesting crops at ground level will lessen the incidence of pests in next season.
  • Before transplanting, seedlings should be treated in copper fungicide or bio pesticide solutions to protect the plants from soil borne diseases.
  • During pruning fruit trees, diseased or broken branches should be destroyed.
  • Large pruning wounds should be covered with Bordeaux mixture to protect the plants from pest or disease attack.
  • Keeping beehives or placing flower bouquets of pollinizer cultivars facilitate better pollination and subsequent fruit set.

Mechanical or Physical Methods of Pest Control

This involves the use of extranl force, tools or machineries or physical pressure to eradicate or reduce the population of pests. The following are examples of physical or mechanical pest control methods:

  • Removal and destruction of egg masses, larvae, pupae and adults of insect pests and diseased parts of plants wherever possible.
  • Installation of bamboo cage cum bird perchers in the field and placing parasitized egg masses inside them for conservation of natural enemies and withholding of pest species wherever possible.
  • Use of light traps and destruction of trapped insects.
  • Use of rope for dislodging leaf feeding larvae e.g. caseworm and leaf folders.
  • Installation of bird scarer in the field where required.
  • Installation of bird perchers in the field for allowing birds to sit and feed on insects and their immature stages viz., eggs, larvae and pupae.
  • Use of pheromones for mating disruption and kill zone creation.
  • Use of pheromone traps for monitoring and suppression of pest population.
  • Use of pheromone traps for mass trapping

Biological Control

Biological control or biocontrol is a method of controlling pests using natural predators such as insects, mites, and plant. This pest control method an important component of integrated pest management (IPM) programs that focuses on predation, parasitism, herbivory, or other natural mechanisms, but typically also involves an active human management role.

There are three basic mechanisms for biological pest control, namely:

  • classical: The introduction of the natural enemy of a pest into the field.
  • Inductive: a situation in which a large population of natural enemies are introduced into the field for quick pest control.
  • Inoculative: Situation in which measures are taken to maintain natural enemies through regular reestablishment.

Natural enemies of insect pests, also known as biological control agents, include predators, parasitoids, pathogens, and competitors. They can have side effects on biodiversity through attacks on non-target species by any of the above mechanisms

Benefits Of Integrated Pest Management

The benefits that IPM can offer make sole reliance upon synthetic pesticides a thing of the past. In the long-term, everyone benefits through a healthier environment. Some of the benefits of IPM include:

  • Promotes sound structures and healthy plants
  • Promotes sustainable bio-based pest management alternatives.
  • Reduces environmental risk associated with pest management by encouraging the adoption of more ecologically benign control tactics
  • Reduces the potential for air and ground water contamination
  • Protects non-target species through reduced impact of pest management activities.
  • Reduces the need for pesticides by using several pest management methods
  • Reduces or eliminates issues related to pesticide residue
  • Reduces or eliminates re-entry interval restrictions
  • Decreases worker, tenant and public exposure to pesticides
  • Alleviates public concern about pest and pesticide-related practices
  • Maintains or increases the cost-effectiveness of a pest management program

Integrated pest management (IPM) program integrates preventive and corrective measures to keep pests from causing significant loss, with minimum risk or hazard to humans and environment. IPM is a flexible and dynamic pest control strategy that needs periodic updates and feedback as information is received from management practice results.

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