MLN Workshop: Agronomic management of maize lethal necrosis -- S Mugo, et al

Agronomic Management of MLN in Maize Improvement

Stephen Mugo, Mosisa Regasa and Anne

Wangui

Presented to the Training Workshop on MLN Diagnosis and Management, Naivasha, 17-19 March

2015

Facts about MLN

MLN is a viral diseaseMLN is caused by 2 virusesMLN is transmitted by insect vectorsSeed transmission of MLN is possible Mechanically transmittedCan be transmitted through infested soil (maize residue) MLN transmission vectors can be aided by wind

MLN Disease Development

Vectors: Presence of aphids and thrips, other

insects

Environment: Conditions

favoring vectors and

disease

Susceptible Germplasm

Virus: Either individual or compound

Community Approaches for MLN Control Awareness creation to all stakeholders

Policy makers, researchers, extension staff, seed producers, farmers

Reduction of the level of inoculumMaize- free “Break” seasonsCrop rotationPlanting earlyCrop diversificationRouging diseased plants

Develop MLN tolerant germplasmTest commercial cultivars and elite germplasmInitiate MLN tolerance/resistance breeding in maize improvement programs

Maize Seed Increase/Breeding nursery

Purposes• The source of seed for the next generation• Beginning of large seed increases • The source of seed to be distributed to large areas

Desired qualities• Adequate amount of seed for planned purposes• Acceptable seed hygiene.


Certified seed

Pre-basic / Basic seed

Nursery


Nursery

Recipient level 1-1

Recipient level 2 -1Recipient level 2 -2

Recipient level 1-2

Recipient level 2 -3

Managing MLN in the Maize Seed Increase/Breeding Nursery

1. Seed source•Use clean seed

• From MLN free nursery• Certified MLN-free seed

2. Grow nursery in MLN free country region•Implement monitoring for MLN

3. Seed Treatment: treat seed with an insecticide


Seed treatments● Clothianidin (Poncho),● Thiamethoxam (Cruiser), ● Imidacloprid (Gaucho)● Imidacloprid + thiodicarb (Aeris)

Demonstrated to provide early stage protection against MLN vectors such as thrips, aphids and beetles.

Experience from SARI 2014

Poncho FS600 at 0.5mg/kernel and Amigo FS275 at1.0mg /kernel seed treatment

• Equally adequately protected the crop from MLN infection via control of the aphids and thrips vector, but for only about 2 weeks after germination.

• This was confirmed from less vector counts and disease incidence in that period.



Seed dressing combined with foliar sprays tested in this study were effective in reducing MLN incidence at early stages of plant growth

Experience from SARI 2014Thunder OD 145 foliar spray treatment alone commencing from the 2nd week after germination was not very effective in MLN reduction but the vector control from that period was significantly reduced:

• The vector had already infected the plants• This intervention was already too late for MLN control

Managing MLN in the Maize seed production fields/ nurseries

Early planted crop

Late planted crop

Managing MLN in the Maize seed increase/breeding Nurseries

4. Ensure clean fieldI. Farm planning – First planted nursery is as far

downwind as possibleII. Crop rotation – avoid MCMV in maize residueIII. Maize-Free period – at least one month free periodIV. Alternative MLN hosts - avoid around the fieldV. Avoid volunteer maize plants

Managing MLN in the Maize seed increase/breeding Nurseries

Maintaining Kiboko breeding and seed production fields MLN-free through “Maize0-free” periodsTarget: At least one-month maize free period with 5km

radiusApproach: Seasonal stakeholders meeting (MoA, County

Govt, CIMMYT, KALRO, Community leaders, farmer group leaders etc)

Experiences: - Three stakeholders meeting- Rainfed farmers respected- Irrigation farmers at first ignored but learnt bitter

lesson- Kiboko has remained MLN-free- Provided forum for research and farmers to

exchange views

Managing MLN in the Maize Seed increase/ Breeding Nursery

5. Control MLN in nurseries5.1 Monitor for viral diseases

• Daily monitor, record, rogue out, and destroy plants with viral symptoms

• If in a new area – send samples for viral diagnostic verification.

5.2. Vector monitoring• Weekly monitor for vectors (thrips/beetles)• Erect insect sticky traps

Managing MLN in the Maize seed increase /breeding Nurseries

6.3. Control MLN in nurseries

• Spray the first spray immediately after germination• Spray up to physiological maturity• Spray insecticides every two weeks

Ø Change chemistries over time• to control all vector species• avoid development of resistance among vectors.

Weekly pesticides for MLN preventionKiboko, Kenya

Pesticide Active ingredient

Group Target pests Mode of action

Marshal 250 EC Carbosulfan250g/l

Carbamate Mites, Thrips, Aphids, Leaf hoppers and Maize stalk borer

Systemic

Duduthrin 1.7 EC

Lambda cyhalothrin17.5g/l

Pyrethroid Thrips, Aphids, Mites, Leaf miners & Caterpillars

Contact

Actara 25 WG Thiamethoxam 250g/kg Neonicotinoid

Aphids,Thrips, Whiteflies and Leaf hoppers

Systemic

Thunder OD 145

Imidacloprid 100g/L + Beta-cyfluthrin 45g/l

Neonicotinoid + Pyrethroid

Thrips, Aphids & Whiteflies

Contact + Systemic




Confidor 200 SL Imidacloprid200g/L

Neonicotinoid Whiteflies, Aphids, Thrips

Systemic

Methogun 90 SP Methomyl 90% w/w

Carbamate Thrips,Aphids Contact + Systemic

Bulldock star EC Beta- cyfluthrin12.5 g/l + Chlorpyrifos250 g/l

Pyrethroid + Organophosphate

Aphids,Caterpillars,Whiteflies,Mites, bollworms

Contact

Colt 480 EC Chlorpyrifos480g/l

Organophosphate

Aphids,Caterpillars,Whiteflies,Mites

Contact




Twiga ace20% SL

Acetamiprid200g/L

NeonicotinoidAphids, Whiteflies Systemic

Cyclone 505 ECCypermethrin10% w/v + Chlorpyrifos35%w/v

Pyrethroid + Organophosphate

Aphids, bollworms, armyworms

Contact

Pyrinex 48 EC Chlorpyrifos480g/l

Organophosphate

Aphids,Caterpillars,Whiteflies,Mites

Contact

Calypso Sc 480 Thiacloprid480g/L

NeonicotinoidAphids, Thrips and Whiteflies

Systemic



Managing MLN in the Maize Breeding Trials

1. MLN data not required from trial● Treat like the nursery

2. MLN data required from trialI. Natural inoculation with MLN

● Do not apply seed treatment● Do not control vectors● Treat and take data as presented in this meeting

II. Artificial inoculation with MLN● Do not apply seed treatment ● May wish to control vectors to avoid spread of viruses to

neighboring fields.● Treat and take data as presented in this meeting

23

We need to increase the pool of MLN resistant germplasm

Questions

1. What have you done in your country

Thank you

Science

MLN Workshop: Agronomic management of maize lethal necrosis -- S Mugo, et al