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Management of Corn Diseases with DuPont™ Aproach® Prima Fungicide

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Foliar Fungicide Use in Corn

  • The need for foliar fungicides for disease management in corn production has increased due to a number of factors
    • Continuous corn acres have increased to meet market demands
    • Reduced tillage and no-till production practices have increased corn residue in continuous corn
    • Disease susceptibility in hybrids is variable
    • Increase in foliar corn diseases in recent years across the Midwest due in large part to favorable environmental conditions for disease development

Factors Affecting Plant Disease

  • Environmental conditions: Temperature and moisture
  • Presence of the pathogen: Previous crop and tillage
  • Host plant: Hybrid selection
Corn disease triangle.

Figure 1. Disease triangle.

Biology of Key Corn Diseases

  • Gray leaf spot, Cercospora zeae-maydis
    • Survives on infested residue
    • Proliferates in wet, warm, humid (>95%), and overcast conditions
Gray leaf spot - corn leaf
  • Common rust, Puccinia sorghi
    • Carried by weather systems from southern locations
    • Proliferates in high humidity (>95%) and cool temperatures (60º-75º F)
Common rust - corn leaf
  • Southern rust, Puccinia polysora
    • Carried by weather systems from southern locations
    • Proliferates in warm (77º-82º F), humid (>95%), and wet conditions
Southern rust - corn leaf
  • Northern corn leaf blight (NCLB), Exserohilum turcicum
    • Survives on infested corn residue
    • Proliferates in prolonged periods of dew or leaf wetness, moderate temperatures (64º-81º F), and overcast conditions

DuPont™ Aproach® Prima Fungicide

  • Dual mode of action, containing: picoxystrobin (strobilurin fungicide) + cyproconazole (triazole fungicide)
  • Manages a broad spectrum of fungal pathogens in corn, while maintaining plant health under stressful conditions
  • Picoxystrobin = better plant health, broad spectrum disease control, reduction in early disease infection
  • Cyproconazole = enhanced disease control spectrum, improved post-infection control with heavy pressure, very effective on NCLB
  • Both active ingredients are highly systemic throughout the plant, providing excellent plant coverage under less than ideal conditions
Dual mode of action in DuPont Aproach Prima fungicide: picoxystrobin provides early disease protection, while cyproconazole provides post-infection control and extended residual activity.

Figure 2. Dual mode of action in DuPont Aproach Prima fungicide: picoxystrobin provides early disease protection, while cyproconazole provides post-infection control and extended residual activity.

Characteristic symptoms of NCLB: ‘cigar shaped’ tan or grayish lesions on leaf surface. Lesions eventually coalesce into necrotic tissue.

Figure 3. Characteristic symptoms of NCLB: ‘cigar shaped’ tan or grayish lesions on leaf surface. Lesions eventually coalesce into necrotic tissue.

Fungicide Efficacy in NCLB Management

  • Research has demonstrated the economic value of fungicide applications depends on the primary factors of disease pressure, application timing, and hybrid susceptibility

Disease Pressure

  • No disease threshold for NCLB
  • High residue due to reduced and no-till practices and corn after corn rotation can lead to an increase in inoculum
  • Even at low levels of NCLB pressure, fungicide application has shown an economic benefit
Average yields from 40 Pioneer® GrowingPoint® agronomy trials in Iowa in 2015 comparing DuPont™ Aproach® Prima fungicide applications with low, moderate, and high NCLB pressure.

Figure 4. Average yields from 40 Pioneer® GrowingPoint®agronomy trials in Iowa in 2015 comparing DuPont™ Aproach® Prima fungicide applications with low, moderate, and high NCLB pressure.

Hybrid Susceptibility

  • Corn hybrids have varying levels of genetic resistance to NCLB
  • Pioneer hybrids vary from a score of a 3 to 6 on a 1 to 9 disease scale (1 = susceptible to 9 = tolerant)
  • Fungicide applications protect yields of all hybrids including moderately-resistant hybrids
Average yields from 40 Pioneer GrowingPoint agronomy trials in Iowa in 2015 illustrating the yield advantage of a fungicide application on Pioneer® brand hybrids with varying disease scores.

Figure 5. Average yields from 40 Pioneer GrowingPoint agronomy trials in Iowa in 2015 illustrating the yield advantage of a fungicide application on Pioneer® brand hybrids with varying disease scores.

Application Timing

  • The goal is to protect yield by preventing infection on the ear leaf and above as the plant enters the reproductive stage
  • DuPont Aproach Prima fungicide is most effective when applied prior to disease infection or soon after infection
  • Fungicides applied at tasseling to early silking stages (VT to R1) have the greatest likelihood of an economic return
Field trial comparing DuPont Aproach Prima fungicide pretassel applications in corn to untreated corn with high NCLB pressure.

Figure 6. Field trial comparing DuPont Aproach Prima fungicide pretassel applications in corn to untreated corn with high NCLB pressure.

Average yields from 40 Pioneer GrowingPoint agronomy trials in Iowa illustrating the value of timely fungicide applications.

Figure 7. Average yields from 40 Pioneer GrowingPoint agronomy trials in Iowa illustrating the value of timely fungicide applications.

Conclusions

  • The need for foliar fungicides to manage key diseases in corn has increased
  • Fungicide effectiveness for managing NCLB depends on 3 primary factors: disease pressure, hybrid susceptibility, and application timing
  • DuPont Aproach Prima is an effective fungicide providing disease control and higher corn yields

Always read and follow all label directions and precautions for use.

The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary.

PIONEER® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents.