Title: How to Identify Nematode Problems and Why It Is Important
1How to Identify Nematode Problems and Why It Is
Important
Richard F. Davis USDA-ARS Crop Protection and
Management Research Unit Tifton, GA
2What is a Nematode?
An Animal Biologically similar to insects Damage
is similar to soil-borne diseases Damage plants
by physically damaging roots and affecting plant
physiology
3Annual Losses in Cotton to Nematodes in the U.S.
Losses to all nematodes were estimated to be 4.7
in 2005 Typical losses are 10 to 30 Losses can
be greater than 50 Losses of 10 to 15 can
easily be overlooked Nematode parasitism often
increases losses to fungal diseases (Fusarium
wilt and Thielaviopsis black root rot)
4The Most Important Nematodes of Cotton in the U.S.
Southern root-knot (Meloidogyne
incognita) Reniform (Rotylenchulus
reniformis) Columbia Lance (Hoplolaimus columbus)
5Damaging nematode species are NOT present in all
fields
6The Damage that Nematodes Cause
Physical damage to roots that impairs the plants
ability to move water and nutrients Root-knot
nematodes cause physiological changes in the
plant that direct some of the plants energy into
feeding the nematode rather than making cotton
fibers
7Symptoms of Nematode Damage
- Most aboveground symptoms are generic expressions
of damage to the roots - Stunting
- Premature wilting
- Yellowing
- Apparent nutrient deficiencies
- Root-knot nematodes cause distinctive galls on
the roots
8(No Transcript)
9- Although damaging nematode species are
widespread - Damaging species are not present in all fields
- Damaging species may be present at levels too low
to cause measurable yield loss (below threshold
levels) - So, the first steps in minimizing losses to
nematodes are to - identify which nematodes are present
- identify how many of each damaging species are
present - To accomplish that, you need to submit a soil
sample to a qualified lab
10Soil sample must be representative
11To get accurate results
- 1) Soil samples must be protected from drying out
- 2) Soil samples must be protected from getting
too hot - Seal samples inside a plastic bag
- Keep plastic bags out of direct sunlight or high
heat - Fill out submission forms as completely as
possible (include cropping history if asked)
12- Lab results should tell you which nematodes need
to be managed, but - Labs differ in the amount of soil they analyze
(100 cm3, 500cm3, pint, etc.) - Labs may base conclusions on different action
threshold levels, which can vary because of - Different extraction methods
- Geographic location
- Soil types
- Other factors
- Therefore, it is usually best to use a lab
familiar with your area, and use the threshold
levels provided by the lab that performed the
analysis
13Dont be hesitant to.. Ask for more
information Ask for more explanation Factor in
your own knowledge of specific fields