How to Identify Nematode Problems and Why It Is Important - PowerPoint PPT Presentation

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How to Identify Nematode Problems and Why It Is Important

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Southern root-knot (Meloidogyne incognita) Reniform (Rotylenchulus ... Root-knot nematodes cause physiological changes in the plant that direct some of ... – PowerPoint PPT presentation

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Title: How to Identify Nematode Problems and Why It Is Important


1
How to Identify Nematode Problems and Why It Is
Important
Richard F. Davis USDA-ARS Crop Protection and
Management Research Unit Tifton, GA
2
What 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
3
Annual 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)
4
The Most Important Nematodes of Cotton in the U.S.
Southern root-knot (Meloidogyne
incognita) Reniform (Rotylenchulus
reniformis) Columbia Lance (Hoplolaimus columbus)
5
Damaging nematode species are NOT present in all
fields
6
The 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
7
Symptoms 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
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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

10
Soil sample must be representative
11
To 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

13
Dont be hesitant to.. Ask for more
information Ask for more explanation Factor in
your own knowledge of specific fields
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