1. Nematode issues in cover cropping systems
Dr. Charles Overstreet
Dr. Josielle Rezende
Deborah M. Xavier-Mis

2. What is the impact of cover crops on nematode problems in Louisiana?
Forage radish

3. Reniform nematode
Southern root-knot nematode

4. Reniform nematode
Southern root-knot nematode

5. Cover Crops and Nematodes
Host status to the nematode
Range from very susceptible to immune
S MS MR R I
Populations may reflect the host status to the nematode
Increase or decrease nematode levels at planting time to main crop
Cover crop may increase, decrease, or not influence yield for the following crop

6. Cover crops that are specific for reducing certain nematodes
Sugarbeet cyst nematode- oilseed radish (Defender) and white mustard (Master)
Northern root-knot – oilseed radish (Defender)
Columbia root-knot- oilseed radish (Control)
Stubby root and lesion nematodes- black oats (Pratex)
Southern root-knot and reniform nematodes- sunn hemp (Tropic Sun)
Southern root-knot nematode- sorghum sudangrass (Green Grazer)

7. Host status of some cover crops to nematodes in Louisiana
Crop Southern root-knot Reniform
Grass
Oats Poor Poor
Rye Poor Poor
Wheat Good Poor
Legume
Austrian winter peas Good Good
Crimson clover Good Good
Red clover Good Good
Subterranean clover Good Poor
Vetch Poor*-Good Good
White clover Good Good
*Cahaba white vetch

8. Host status of some cover crops to nematodes in Louisiana
Crop Southern root-knot Reniform
Crucifers
Canola Good Poor
Oilseed Radish Good Poor
Turnip Good Poor
White Mustard Good Poor

9. Southern root-knot nematode reproduction on some cover crops
Mi race 3 on cover crops. The cover crops are ‘Bigbee’ berseem clover (Trifolium alexandrinum), ‘Dixie’ crimson clover, ‘AU Sunrise’ crimson clover (T. incarnatum), common hairy vetch, AU Early Cover hairy vetch (Vicia villosa), ‘Paradana balansa’ clover (T. balansae), ‘Cherokee’ red clover (T. pratense), Cahaba’ White vetch (V. sativa), and ‘Wrens Abruzzi’ rye (Secale cereale). Pots were inoculated with 8,000 nematode eggs. Eggs were extracted from roots 60 d later. Bars are the mean of eight replicates and two trials (n = 16). Bars with the same letter are not different (P > 0.05).
Timper et al., J Nematology 38: 83–89.

10. Galling on cotton after the cover crop
Timper et al., J Nematology 38: 83–89.

11. Cotton yield after the cover crop
Yield in pounds/acre
Timper et al., J Nematology 38: 83–89.

12. Planting date impact on southern root-knot nematode in Wren Abruzzi rye and Coker 797 wheat
Date Root-knot Adult
Crop Planted Sampled Juveniles egg masses
Rye 1 Oct Nov
3 Dec
3 Jan
Rye 1 Nov Dec
3 Jan
Wheat 1 Nov Dec
3 Jan
Wheat 1 Dec Jan
Johnson and Motsinger, J Nematology 22:

13. Quesenberry et al. , 2014. Crop and Pasture Science DOI: 10
Quesenberry et al., Crop and Pasture Science DOI: /CP13437

14. Southern Root-knot galling
Osceola white clover
Ocoee white clover
O koi
Quesenberry et al., Crop and Pasture Science DOI: /CP13437

15. Barrel medic (Medicago truncatula)
Southern root-knot nematode damage
Resistant breeding line
Susceptible breeding line
Dhandaydham et al., J Nematology 40:46-54

16. Management plans using cover crops in fields with nematode problems
Know which type of nematode is present in the field
Avoid cover crops that are good hosts for that nematode if possible
Planting date can be very important
65° F important temperature to remember
Termination in spring can be important

17. Cover crops and plant-parasitic nematodes
Winter cover crops may not suppress nematodes effectively
Considerable variation in Southern root-knot nematode from one location to another
Weeds can serve as suitable hosts for nematodes and can reduce effectiveness
Unknown what happens when mixtures of two or more cover crops are used together