Nematodes are Highly Underrated Pests Most numerous animal (s) in the world Are the second most in number of animal species Over 6000 known plant-parasitic species Nematodes attack all crop plants Present in all cotton growing areas of the U.S.
Plant Nematode Facts Mainly plant root parasites Very small - mostly microscopic Five life stages (plus egg) Mostly wormlike in shape Some female nematodes swollen Life cycle - every 20-30 days Some females can produces 300-400 eggs Over one season - 1 female = 8 billion and more nematodes (hence the problem!!)
Purpling of Cotton Leaves by Reniform Nematodes J.R. Rich
Plant Root Damage Stunted roots Fewer feeder roots Root galling and swelling Root cell death or cell malfunction Openings for disease organisms
Root-Knot Nematode Galling on Roots, Not Very Apparent J.R. Rich
Female Root-Knot with Eggs, Root is the Size of a Pinhead R.S. Hussey
Reniform Nematode Females Partially inside Roots, No Root Galling Females teased out and laid on top of root C. Overstreet
Nematode Damage Symptoms When damage symptoms are observed in the field, losses have been occurring over several years Most times nematodes cause economic losses without obvious symptoms A small problem this year makes for a large one the next year
Comparison of Nematode Damage Symptoms on Cotton Root-KnotReniform Galled roots No galling Little leaf discoloring Leaf purpling Irregular patches General decline Patches obvious Less obvious Sands, loams Loams, clays Lower numbers Higher numbers
Nematode Problem Assessment Nematode Problem Assessment
Know Your Nematodes Each nematode species is ‘different’ Management techniques should be ‘nematode specific’ Rotations must be planned for ‘key’ nematode pests Nematicide rates can be adjusted for nematode species
Problem Identification Foliar symptoms – stunted ovals/decline Root symptoms – roots galled/stunted Cropping history – declining yields and previous host crops Laboratory analysis – which nematode type and numbers are present
Nematode Soil Samples Problem ID Take anytime during crop maturity and prior to planting, best time is soon after harvest Can take samples for nematodes when collecting soil fertility samples Split soil samples, one for nematode analysis and one for fertility (1 pint each) Remember extra care is required for nematode samples
Handling Nematode Soil Samples Sample 8-10” deep if possible Sample only in moist soils – Not dry or wet Only use plastic bags which prevents soil drying Do not allow samples to become hot or cold
Tools for taking nematode soil samples Choice of sampling tools Plastic bag Permanent ink marker Bucket
Ten Acre Sampling Patterns (Take 15 To 20 Cores) Centered GridIntersected Grid Zig ZagRandom
Temik 15G Product Information Sold only as a 15% granular formulation Formulation usually clay based Used at-planting as a band or in-furrow Pinhead square side dress applications can also be made Temik 15G rarely kills nematodes (mainly paralyzes them)
Telone II Product Information Sold as liquid formulation only Movement by fumigant action in the soil Applied preplant injected to 14 inches depth (do not apply in clay subsoil) Usually applied with a single in-row chisel in cotton Telone II kills nematodes on contact
Sold only as a seed treatment Combination of fungicide, insecticide, and nematicide Chemicals are present on the seed at the time of planting Avicta Comptete Pak Product Information
Telone, Vydate and Temik Are Restricted Use Pesticides Reminder - both products have specific use restrictions!! In Florida U.S.A., Temik has special reporting and use requirements. Temik 15G forms and other requirements can be found at FDACS Web Site - http://www.safepesticideuse.com
Cotton Nematicide Rates Varies Dependent Upon: Soil Type, Location, Nematode Species Temik 15G (In Furrow) Ranges from 3.5 lbs/a to 7 lbs/a at the time of planting Telone II (In Row, Single Chisel) Ranges from 3 gal/a to 5 gal/a applied at least 7 days prior to planting
Farmer Field Demonstration No Treatment ↓ Telone II ↓ M. Donahoe
Rotation Know what nematode(s) are present Use poor or nonhosts crops and rotate for at least two years Consider using a nematicide if rotating only one year Reniform nematode rotation: corn, sorghum, and peanuts are nonhosts; tobacco and soybeans are poor to moderate hosts. Cucurbits are good hosts. Southern root-knot nematodes have a wide host range but sorghum and peanut are fairly resistant.
Sanitation Notes Control weeds, many are nematode hosts including Morningglory, Florida Pusley, Tropical Spiderwort, Nutsedge etc. Prevent crop regrowth in peanut and cotton to stop nematode population after harvest Perennial grass rotation (bahiagrass) does not work with weed hosts present
Nematode Weed Hosts in Bahiagrass Pasture J.R. Rich
Is GPS/GIS Variable Rate Nematicide Application Feasible? This is ‘doable’ technology!! System Needs: Accurate nematode population distribution map of a field, alternatively, a yield monitor map linked to nematode populations Programmed GPS unit programmed for nematicide rate based on the nematode distribution map Equipment suitable for nematicide rate adjustment
What Is The Link Between Nematodes And Fusarium Wilt In Cotton? Fusarium is a soilborne fungus that causes cotton to wilt and die. Most cotton varieties have Fusarium wilt resistance thanks to efforts by breeders. However, when nematodes are present, they break this Fusarium wilt resistance. Thus, two problems result, nematode damage and Fusarium wilt in cotton.
Cotton and Peanut Rotation Cotton is attacked by the southern root-knot and reniform nematodes. Peanut is affected by the peanut root-knot and lesion nematodes. This makes for a good rotation to reduce nematode problems in each crop. However, do not use the same crop two years in a row. Cotton, peanut, cotton, peanut are better rotations but must be supplemented with low nematicide rates. The best rotation is adding another crop in the sequence – corn (sorghum), soybean (resistant), or perennial grass crops.
Additional Information Visit the U.S. Cotton Nematode Research and Education Committee site at: http://www.cotton.org/tech/pest/nematode Visit the U.S. Cotton Nematode Research and Education Committee site at: http://www.cotton.org/tech/pest/nematode