Plant nematodes of agricultural importance : a colour handbook

153 Pages·2007·12.56 MB·English

by  John Bridge

Plant Nematodes
of Agricultural
Importance
A Colour Handbook
John Bridge
Tropical Plant Nematology Advisor, Emeritus Fellow
CAB International UK Centre, Egham, Surrey, UK
James L. Starr
Professor, Department of Plant Pathology and Microbiology
Texas A&M University, College Station, Texas, USA

MANSON
PUBLISHING
Copyright © 2007 Manson Publishing Ltd
ISBN-10: 1-84076-063-X
ISBN-13: 978-1-84076-063-7
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Plant Protection Handbooks Series
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Biddle & Cattlin: Pests and Diseases of Peas and Beans – A Colour Handbook
Blancard:Cucurbit Diseases – A Colour Atlas
Blancard:Tomato Diseases – A Colour Atlas
Blancard:Diseases of Lettuce and Related Salad Crops – A Colour Atlas
Fletcher & Gaze: Mushroom Pest and Disease Control – A Colour Handbook
Helyeret al:Biological Control in Plant Protection – A Colour Handbook
Koikeet al:Vegetable Diseases – A Colour Handbook
Murrayet al:Diseases of Small Grain Cereal Crops – A Colour Handbook
Wale et al:Pests & Diseases of Potatoes – A Colour Handbook
Williams: Weed Seedlings – A Colour Atlas
Contents
Preface 4 Chapter 7 Tree, Plantation, and Cash Crops 97
Introduction 98
Chapter 1 Plant Nematode Biology and Banana and plantain: Musaspp. 98
Parasitism 5 Black pepper: Piper nigrum 106
Introduction 6 Citrus crops 108
Migratory ectoparasites 8 Coconut:Cocos nucifera;
Migratory endoparasites 11 Oil palm: Elaeis guineensis 111
Sedentary endoparasites 14 Cotton:Gossypiumspp. 114
Tobacco: Nicotiana tabacum 120
Chapter 2 Grain Legumes 19 Coffee:Coffeaespp. 122
Introduction 20 Sugarcane:Saccharum officinarum 125
Soybean:Glycine max 20 Pineapple:Ananas comosus 128
Peanut (groundnut): Arachis hypogeae 27 Deciduous fruit and nut crops 130
Other beans and peas 32
Chapter 8 Collection, Extraction, and
Chapter 3 Vegetables 39 Preservation of Nematodes for Diagnosis 135
Vegetable crops 40 Introduction 136
Collecting samples 136
Chapter 4 Flowers 45 Care of samples after collection 139
Flower crops 46 Extraction of nematodes from soil and
plant samples 140
Chapter 5 Cereals 51 Staining nematodes in plant tissues 143
Rice:Oryza sativa 52 Nematode identification 144
Maize:Zea maysL. 61
Wheat:Triticum aestrivum 64 Bibliography 145
Chapter 6 Root and Tuber Crops 69 Glossary 146

Introduction 70
Potato:Solanum tuberosum 70 Index 149
Sweet potato: Ipomoea batatas 77
Yams: Dioscoreaspp. 79
Cassava:Manihot esculenta 84
Taro: Colocasia esculenta 86
Ginger:Zingiber officinale 88
Carrot:Daucus carota 90
Sugar beet: Beta vulgaris 92
4
Preface
Soil and plant nematodes are one of the most nematodes. To be certain of the association between
numerous groups of organisms occurring in the soil. particular nematodes, the organisms have to be
They are microscopic animals and, with a few extracted from the soil, roots, or other plant material
exceptions, are not visible to the naked eye. The and identified microscopically.
majority of the soil-borne nematodes are not pests of This book is written to help people working with
crops and feed on other organisms, particularly plants to have an improved understanding of plant
bacteria and fungi. Those that are parasitic on crop nematode pests and enable them to give better
plants can be very damaging and, because of their informed diagnoses, where possible, of the damage
microscopic size, associating them with crop damage caused by the very wide range of nematodes that are
is therefore mainly dependent on determining the known to parasitize and injure plants. The colour
symptoms of their effects on plants or plant growth. photographs provide an extensive range both of
Some of the parasitic nematodes do produce symptoms of nematode injury and of nematodes
characteristic and recognizable symptoms of damage themselves, observed in the field or microscopically
but many of them only produce nonspecific in plant tissues, throughout the world. There is an
symptoms. The damage and the symptoms caused introductory chapter on biology and parasitism.
can be visible above-ground; however, apart from Parasitic nematodes are discussed under the crops
poor growth and yield of the plants, the specific that they are known to attack. Crop chapters are
nematode-induced damage symptoms can often only divided into grain legumes, vegetables, flowers,
be seen in the below-ground plant organs, mainly the cereals, root and tuber crops, and tree, plantation,
roots, rhizomes, bulbs, corms, and tubers. and cash crops. Concise information is provided for
When the above-ground symptoms are the result the nematodes in these crop sections on their
of nematodes feeding on roots below ground, these distribution, symptoms and diagnosis, management,
symptoms are often similar to those seen when there and identification. A final chapter outlines the
are water or nutrient deficiencies in the soil. These so- common methods used in nematology.
called poor soils or ‘tired soils’ are often a result of a A glossary of nematological terms and a biblio-
build-up of large populations of parasitic nematodes graphy of the most important nematology texts and
in the soil. The main above-ground symptoms of papers have also been produced to help the reader.

nematode root damage are poor or stunted growth, In the compilation of this book, we are grateful to
reduced foliage, twig/branch dieback, chlorosis or our nematological colleagues for their advice,
yellowing of leaves, poor fruit or seed production support, and encouragement. We also wish to thank
and, in extreme cases, wilting and early senescence or those who have generously allowed us to use their
death of plants. The below-ground symptoms are photographs; these persons are acknowledged
related to the health of the root systems and other specifically in the legends of the photographs. Lastly
structures which can be reduced in number, suffer we thank Monica and Marylou, our long-suffering
from necrosis and rot, or have abnormal growths wives, for their patience and support of our efforts.
such as swellings or galling. Generally, it is necessary
to examine roots and other plant tissues to establish John Bridge
a connection between damage symptoms and James L. Starr
5
CHAPTER 1
Plant Nematode
Biology and
Parasitism
• INTRODUCTION • SEDENTARY ENDOPARASITES
• MIGRATORY ECTOPARASITES Meloidogynespp.;Nacobbusspp.;
GloboderaandHeteroderaspp.;
Belonolaimusspp.;Xiphinema, Longidorus,
Rotylenchulusspp.;Tylenchulus sp.
andParalongidorusspp.;Anguina,
Aphelenchoides,andDitylenchusspp.
• MIGRATORY ENDOPARASITES
Pratylenchusspp.;Radopholusspp.;
Hoplolaimusspp.;Ditylenchusspp.
6 PLANT NEMATODE BIOLOGY AND PARASITISM
Introduction
Plant parasitic nematodes are principally aquatic 50 eggs/female to those that may produce more
animals requiring free moisture for activity; they than 1000 eggs/female.
inhabit the moisture films surrounding soil particles All crop plants are susceptible to at least one
and the moist environment of plant tissues. Nearly nematode species. Thus the potential exists for
all plant parasites spend a portion of their life cycle nematode parasitism in all climates on any crop.
in the soil. Most nematodes are adapted to the sub- The degree of damage caused by nematodes to the
tropical to tropical climates, but some are adapted to crop in any given field is closely related to the
the cooler climates of the more northerly and nematode population density, especially for annual
southerly latitudes or to higher elevations. Any crops. Precise data are lacking on the distribution
climate that supports higher plants will also support of most agriculturally important nematodes, but
a population of plant parasitic nematodes that are the distribution of the cyst nematodes on potato in
similarly adapted to that climate. Like most Europe and on soybean in the central USA, and of
invertebrate organisms, their level of activity is root knot and reniform nematodes on cotton in the
closely linked to the environmental conditions, southern USA is well documented. In each of these
especially temperature. cases, there are regions in which more than 50% of
Most nematodes and the problems they cause are the fields are infested with the problem nematode
typically associated with coarsely textured soil with species. In many other fields, even though
relative large pore spaces. Soils with sand contents potentially damaging species are present, their
of greater than 60% fulfill these conditions, as do numbers and reproductive potential in that
soils with high concentrations of organic matter or environment is insufficient to cause measurable
with low sand concentrations but with a high yield losses. With perennial crops, even low initial
degree of aggregation of silt and clay such that pore numbers of nematodes under conducive conditions
spaces are increased. However, substantial can increase sufficiently to cause substantial yield
nematode damage has been observed in nearly all suppression.
soils types. Although most nematodes are root parasites,
The nematode life cycle is relatively simple, there are nematodes adapted to parasitism in nearly
consisting of the egg, four juvenile stages, and the all plant tissues and organs. Plant parasites can be

adults. The length of the life cycle varies greatly conveniently classified based on their mode of
among the different genera, ranging from a few parasitism (Table 1). The symptoms of nematode
days to nearly 1 year under optimal environmental damage vary greatly and may be quite indistinct.
conditions and a favourable host. Nematodes It has been documented that with some crops a
reproduce both sexually and by various asexual, suppression of yield occurs prior to the expression of
parthenogenetic mechanisms. Males are common diagnostic symptoms.
in species reproducing sexually, but are generally This text provides general information on the
rare or unknown in species reproducing partheno- biology and parasitic habits of the most agriculturally
genetically. Reproductive potential also varies important genera of plant parasitic nematodes and
greatly with genera, with some producing less than specific information on the most important species.
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INTRODUCTION 7
TABLE 1 Parasitic habits and examples of nematode genera
1. Ectoparasites: generally the nematodes remain on the surface of the plant tissues, feeding by inserting the stylet
into cells that are within reach
• Foliar ectoparasites: ectoparasites feeding generally on epidermal plant cells of young leaves, stems, and flower
primordia often enclosed by other foliage (Anguina, Aphelenchoides, Ditylenchusspp.)
• Root ectoparasites:
•• Ectoparasites with short stylets feeding mainly on outer root cells and root hairs (Tylenchorhynchus,
Trichodorus,Paratrichodorus, some Helicotylenchusspp.)
•• Ectoparasites with long stylets that can be inserted deep into root tissues normally at the growing tip (some
can become relatively immobile) (Belonolaimus, Cacopaurus, Criconemoides, Dolichodorus,
Hemicriconemoides, Hemicycliophora, Longidorus, Paralongidorus, Paratylenchus, Xiphinema spp.)
2. Migratory endoparasites: all stages of the nematodes can completely penetrate the plant tissues, remaining mobile
and vermiform and feeding as they move through tissues; they often migrate between the soil and roots
• Foliar endoparasites: endoparasites in stems, leaves, flower primordia, or seeds (Aphelenchoides,
Bursaphelenchus [Rhadinaphelenchus] cocophilus,Bursaphelenchus xylophilus,Ditylenchus angustus,
Ditylenchus dipsaci)
• Below-ground endoparasites: all stages of endoparasites are found throughout different tissues in roots, corms,
bulbs, tubers, and seeds (peanuts) (Aphasmatylenchus,Ditylenchus[some],Helicotylenchus[some],
Hirschmanniella,Hoplolaimus,Pratylenchoides,Pratylenchus,Radopholus,Rotylenchus[some],Scutellonemaspp.)
3. Sedentary endoparasites: immature female or juvenile nematodes completely enter the plant tissues, develop a
permanent feeding site, become immobile, and swell into obese bodies. Expansion of plant tissues (galling) can
occur around nematodes (Achlysiella, Globodera, Heterodera, Meloidogyne, Nacobbus, Punctodera spp.)
4. Semi-endoparasites: immature female or juvenile nematodes only partially penetrate the roots, leaving the posterior
half to two-thirds of the body projecting into the soil. Nematodes become immobile in a fixed feeding site and the
projecting posterior of the body becomes enlarged. (Some migratory nematodes can also be found in a semi-
endoparasitic position on the roots.) ( Rotylenchulus, Sphaeronema, Trophotylenchulus, Tylenchulus spp.)
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8 PLANT NEMATODE BIOLOGY AND PARASITISM
Migratory ectoparasites
This group includes a large number of genera and species. Many ectoparasitic species are only
rarely associated with crop damage. Among the migratory ectoparasites most noted as
aggressive pathogens (those that typically cause extensive damage to the host) of several crop
species are the sting nematode (Belonolaimus longicaudatus), the sheath nematode
(Hemicycliophora arenaria), the dagger nematodes (Xiphinemaspp.), the needle nematodes
(Longidorusspp.,Paralongidorusspp.), and the stubby root nematodes (Paratrichodorusand
Trichodorusspp.,7). Various stunt nematodes (Tylenchorhynchus (1),Quinisulcius, and
Merliniusspp.) and ring nematode (Criconemoidesspp.) (2) are less commonly associated with
substantial yield losses but can be economically important on selected crops. Some
Helicotylenchus(3) and Rotylenchusspecies feed as ectoparasites. All life stages of the migratory
ectoparasites, except the egg, are parasitic. Root feeding nematodes with short stylets feed on the
epidermal and outer cortical cells often at the root tips (4), those with longer stylets feed deeper
in the cortex. Eggs are laid singly in the soil and the life cycle is usually straightforward, with
each stage having to feed on a suitable host in order to develop to the next stage (5).
Reproduction is by both sexual and asexual systems.
1 2

1 Females and egg of Tylenchorhynchus annulatus. 2 Criconemoidesfemale.
3 4
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M 3 Helicotylenchus indicusfemale. 4 Tylenchorhynchus maximusfeeding as an ectoparasite
on a root tip.
MIGRATORY ECTOPARASITES 9
5
(J1)
J4
J2 J3 Mature Eggs in soil
female
Feed on
surface
of root All stages feed
Eggs laid in soil
5 Life cycle of the ectoparasite Longidorusspp.
Belonolaimus spp. 6
The sting nematode, Belonolaimus longicaudatus, is

a migratory ectoparasite with a long feeding stylet
(6,25) that allows it to pierce roots and feed on the
cortical tissues several cell layers deep in the roots.
The sting nematode does not induce any specialized
feeding sites, but causes extensive cellular damage
and necrosis of cortical tissues. Distribution of this
species is strongly influenced by soil texture and
temperatures. The nematode is found only in the soil 6 Anterior end of a female Belonolaimus longicaudatus.
in warm climates and requires very sandy soils
(typically with greater than 85% sand content). .P
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During the warmest parts of the year, population
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densities may decline in the upper soil profile, with M
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most nematodes being found 15–30 cm deep. The A
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reproductive potential of the sting nematode is
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moderate and rarely do population densities exceed
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100 nematodes/100 cm3soil. BE