Dr Albert Rovira,
CSIRO Division of Soils, Glen Osmond, South Australia 5064
Ecology, epidemiology and control of take-all, Rhizoctonia bare patch and cereal cyst nematode in wheat
I consider it an honour to have been asked to present the Daniel McAipine
Memorial Lecture. In many ways, since I ventured into plant pathology in the
early 1970s after a career in soil and rhizosphere microbiology, I have followed
in the footsteps of Daniel McAlpine. It was McAipine (1 902; 1904) who first
isolated and identified the fungus Ophiobolus graminis (now Gaeumannomyces
graminis (Sacc.) Arx & Olivier var. tritici Walker) as the causative agent
for the root disease take-all of wheat in Australia. He was so concerned with
the severe losses take-all was causing that he distributed a questionnaire to
farmers to get more information on the disease with the aim of developing
control measures. Here, my interests were similar to those of McAlpine's - to
improve our understanding of the disease in the field so that farmers can
overcome the problem and increase grain yields.
Take-all causes large yield losses throughout the world, and initially the aim
of my research was to study the ecology and epidemiology of take-all in the
field in relation to rotation and tillage systems. However, the scope of the
research expanded when early field experiments with soil fumigation and
nematicides demonstrated the extent and magnitude of the cereal cyst nematode (CCN)
problem caused by Heterodera avenae Woll. My interests expanded further when
farmers' reports and our own tillage research highlighted Rhizoctonia bare
patch, caused by Rhizoctonia solani Kdhn, as a major impediment to the adoption
of conservation tillage practices.
Our soil fumigation studies showed that farmers were suffering huge losses
through root diseases, despite the fact that the diseases had been recognised in
the field for 40 to 100 years and a great deal of scientific effort had gone
into understanding them.
I decided that if we were to help farmers overcome these problems and increase
productivity, we should concentrate on field experiments, the results of which
would be expressed not only in terms of pathology, but also in terms of yield.
In this way, farmers could assess the losses they were suffering and decide
whether it would be worth their while adopting strategies to minimise these
losses. This has been the philosophy behind my research which has been supported
by Wheat Research Council and CSIRO.
I will present some of the highlights of the research which is the result of a
team effort. I have been extremely fortunate that such dedicated and
enthusiastic people have been associated with the research from its inception.
A great deal of work has been conducted in Australia on these three cereal root
diseases and I refer readers to recent reviews on take-all (Rovira et aL 1991),
Rhizoctonia bare patch (MacNish and Neate 1991), and cereal cyst nematode (Brown
Soil fumigation to determine the importance of soilborne root diseases
Field trials in south-eastern Australia have shown yield responses of 15% to
450% following soil fumigation (Rovira and Ridge 1979). Responses at six sites
in four seasons are illustrated in Figure 1.
By conducting trials which include fertiliser treatments and selective biocides
as well as fumigation it was possible at several sites to compartmentalise the
responses and separate the effects of nutrient supply, nematode control and
fungal control (Meagher et al. 1978; Rovira and Simon 1985). Fumigation through
areas identified as Rhizoctonia patches in a preceding crop and also through
surrounding areas of the good plant growth on calcareous sandy soils enabled
Simon and Rovira (1985) to demonstrate yield response of 322% and 29% inside and
outside the patches, respectively. When this information was combined with
aerial photographs which showed that the patches made up 18% of the crop, it was
possible to estimate the yield loss from Rhizoctonia bare patch.
Development of long-term field trials
In the mid-1970s ICI and Monsanto introduced 'knock-down' herbicides which
enabled crops to be direct drilled into uncultivated soil. At this stage little
had been published, either locally or overseas, on the effects of tillage on
cereal root diseases. Because cereal root diseases appear to be more serious in
southern Australia than in Europe and the United States, I decided to expand the
scope of the research to include different tillage systems in the rotation
trials at three sites typical of the major cereal growing areas of south-eastern
Figure 1. see Australasian Plant Pathology Vol. 19 (4) 1990
One site was at Avon near Balaklava 100 km north of Adelaide with a typical
mallee environment of calcareous sandy soils (Classification Gcl, solonised
brown soil, Northcote et al. 1975) and an average annual rainfall of 350 mm and
a drought frequency of one year in three. This trial consisted of five 2-year
rotations, viz. continuous wheat, grass/medic pasture-wheat, medic
pasture-wheat, peas-wheat, and oats-wheat; two tillage systems, conventional
cultivation and direct drilling with the SIRODRILL (Venn et aL 1982), were
applied to the first four rotations while the oats-wheat rotation was sown
following cultivation but not by direct drill . Six replicate plots, each 200 m
long, of each treatment were set up. Two identical phases of the trial were set
up one year apart so that each year one of the phases was in wheat while the
other was in the alternative rotation. The first phase with the alternate
rotations was set up in 1978, and the second in 1979, in each case following a
wheat crop from a long-term medic pasture-wheat rotation.
The second site was at Kapunda 100 km northeast of Adelaide with a red-brown
earth soil (Classification Dr2.33, red duplex soil, Northcote et al. 1975), an
average annual rainfall of 496 mm and a drought frequency of one year in ten.
There were three 2-year rotations, viz. continuous wheat, lupinswheat, and
grass/subterranean clover pasturewheat, with three tillage systems, viz.
conventional cultivation following the district practice of three cultivations
to 5-7 cm with a dart point cultivator, reduced-tillage with one cultivation,
and direct drilling initially with the SIRODRILL and after 1986 with a narrow
sowing point. As at Avon, two identical trials were set up a year part to
provide the two phases. The paddock had been under grass-clover pasture for 9
years before Phase I was sown to wheat using the three tillage systems in 1983;
Phase II was started with wheat using the three tillage systems in 1984.
Neither Avon nor Kapunda sites had a significant level of CCN, so detailed
research on this disease was conducted on a third farm at Calomba where it was
the major problem. Soil and climate at Calomba are similar to those at Avon.
Extensive research on CCN was also conducted throughout South Australia (Rovira
et al. 1981; King et al. 1982).
Effects of rotation and cultivation The results from both Avon and Kapunda
demonstrated the importance of grasses in building up the levels of the take-all
fungus in soil, the damage to roots by the take-all fungus and the conse uent
reduced yields .q of the following wheat crops.
The incidence of take-all in roots in late August at Avon in 1979 accounted for
53% and 67% of the variation in grain yield of wheat sown by direct drilling and
following cultivation, respectively (Figure 2). Direct drilled wheat after a pea
crop or medic pasture, each sown by direct drilling, had a higher incidence of
take-all and a lower grain yield than wheat sown with cultivation following peas
and medic which had also been sown into cultivated soil. These results reflect
the fact that, at that time, cultivation was necessary to control grasses in
legume crops and sown pastures (Figure 3) and hence, in the mallee environment,
continuous direct drilling was not a practical proposition. In the mid 1980s,
the development of selective herbicides, which remove grasses from grain legume
crops and pastures, improved the prospects for direct drilling. As the trial
developed at Avon and grass-control herbicides were used, comparable yields were
obtained with direct drilling and cultivation, indicating that control of
take-all by the appropriate rotations is necessary before adopting direct
Figure 2&3. see Australasian Plant Pathology Vol. 19 (4) 1990
Results from the Kapunda site have confirmed this need for grass management
in order to control take-all and improve yields. Figure 4 expresses the benefits
of take-all control in terms of the yield potential as expressed in terms of the
April-October rainfall model of French and Schuitz (1984). This model has proven
a valuable tool to demonstrate the effects of different practices on yield. I
believe that it is a useful concept which plant pathologists could apply to
other crops and diseases. Figure 4 shows that in our plots yields went from 30%
to 80% of the potential with high and low take-all, respectively. The average
yield for the district did not change significantly between the two years
indicating the scope for increased yields if farmers adopted grass management
Figure 4. see Australasian Plant Pathology Vol. 19 (4) 1990
Link between rainfally incidence of take-all and grain yield Results over
eight years at Avon demonstrated an average annual yield response in wheat from
controlling take-all of 42% (viz. average yields went from 1.2 t/ha to 1.7
Our research has shown that yield losses were strongly related to disease
incidence on wheat roots and rainfall in September (r2 = 0.91) but were poorly
related to disease incidence alone. Adequate rainfall in spring was necessary to
allow the development of the take-all fungus on and inside roots and to reduce
yield. Survival of inoculum of the pathogen until the following growing season,
as indicated by the percentage of wheat plants infected with take-all, was also
influenced by spring rainfall. A regression model was developed to predict the
incidence of take-all in a wheat crop from the incidence of take-all and the
August-September rainfall the previous season (r2 = 0.96) (Roget and Rovira
Use of artificial inoculum to screen for resistance to take-all One problem
of screening cultivars for resistance to take-all in the field is the variation
in disease levels in most fields. The development of artificial inoculum of
take-all with sterile ryegrass or millet seeds by Simon et al. (1987) enabled us
to screen 3500 cultivars from the Australian WheatCollection for resistance to
take-all. In this research, done over four seasons, we used either single rows
or microplots and found a considerable range in resistance or tolerance between
cultivars (Simon and Rovira 1985).
Biological control From my research experience on the microbiology of the
rhizosphere, I maintained an interest in the interactions between root pathogens
and rhizosphere microorganisms as a possible factor in the biological control of
root diseases. In 1971-72 while a Senior Research Fellow at the University of
Bristol, UK, I worked with Dr Richard Campbell to show by scanning electron
microscopy that, in axenic sand systems, bacteria of the Pseudomonas spp.
attached themselves to hyphae of the take-all fungus growing on roots and caused
the lysis of the hyphae (Rovira and Campbell 1975).
Dr Richard Smiley worked in my laboratory during 1971 and 1972 and further
developed his doctoral research on the effects of ammonium-N and nitrate-N on
the pH of the rhizosphere. Smiley demonstrated that with ammonium-N there was a
fall in the pH of the rhizosphere and a build-up of fluorescent pseudomonads
suppressive to the take-all fungus (Smiley 1978a,b).
The visit by Dr Jim Cook, from the USDA/ARS Cereal Root Diseases Laboratory,
Washington State, for eight months in 1974 working on biological control of
take-all, acted as a great stimulus to my interest in the topic. This led to our
hypothesis that the fluorescent pseudomonads were a major factor in making
long-term wheat soils suppressive to take-all (Cook and Rovira 1976). This
publication helped to create the interest in pseudomonads as biocontrol agents
and was followed by a review in which I presented an optimistic but realistic
approach to the manipulation of the rhizosphere microfiora to increase plant
production (Rovira 1985).
This research on biological control of take-all was expanded when Dr Graham
Wildermuth undertook his PhD at the Waite Institute with Dr Jack Warcup and me.
Amongst other things, this research led us to postulate a mechanism for the
suppression of take-all in the rhizosphere associated with the phenomenon of
take-all decline (Wildermuth et al. 1979; Rovira and Wildermuth 1981) in which
pseudomonads with suppressive activity build up on and in the lesions on roots
caused by the take-all fungus. Wildermuth demonstrated that, in suppressive
soils, hyphae of the take-all fungus are colonised by bacteria as the hyphae
grow from propagules towards roots.
The visits in 1983 by Drs Jennifer Parke and David Weller from the USA as
post-doctoral fellows further developed our expertise in biological control of
take-all and led to the appointment of Dr Maarten Ryder to apply modern
biotechnological methods to this area of research with support from Monsanto
Of course, the ultimate test for biological control of root diseases will be in
the field with its wide range of edaphic and climatic conditions and, while the
technique offers some exciting possibilities, there are many hurdles to overcome
before we can offer farmers biological control as a method of controlling
take-all. At this stage, we still lack knowledge on many of the processes
involved in biological control in field soils and, hence, we can neither predict
when it will succeed nor why it has succeeded or failed in different seasons and
Rhlzoctonia bare patch
Rhizoctonia root rot or bare patch, which is a severe disease of cereals in
many calcareous sandy soils of South Australia (Samuel and Garrett 1932), has a
wide host range making it impossible to control by rotation. The strong
competitive saprophytic ability of Rhizoctonia in soil allows it to colonise
particulate organic matter; Neate (1987) found that propaguies of Rhizoctonia
were some four times more abundant in the 0-5 cm layer of field soil than in the
5-1 0 cm layer. Farming practices which conserve organic matter on or near the
surface favour this pathogen and account for this disease being a serious
problem in direct drilled crops in southern Australia (Rovira 1986).
Effects of cultivation, rotation and autumn chemical fallow The practice of
herbicides replacing the plough improves soil properties and prevents
degradation; it is a necessary step to build up organic matter in the move
towards sustainable cropping systems (Rovira 1990; Rovira et al. 1990). However,
it became apparent from research and reports from farmers in Western Austrai'ia,
South Australia, Victoria and southern New South Wales that Rhizoctonia bare
patch was becoming a serious problem associated with direct drilling in soils
and districts where it had not previously caused obvious damage.
Research at Avon (Rovira 1986) demonstrated that the damage to rqots by
Rhizoctonia and the consequent areas of crop lost as patches of poor growth were
greater in direct drilled wheat than in wheat sown following cultivation (Figure
5). There was no effect of rotation on the damage to roots, but rotation
affected the areas lost to patches; this area was lowest in wheat following
medic pasture and peas. The higher available nitrogen in the soil following
grass-free medic pasture and peas than following wheat or grassy pasture enabled
the plants to better tolerate root damage which is consistent with the report by
MacNish (1985) that fertiliser nitrogen reduced Rhizoctonia bare patch.
Figure 5. see Australasian Plant Pathology Vol. 19 (4) 1990
The practice originally recommended for direct drilling of cereals in
southern Australia was based on the 'Graze, Spray, Seed' message, whereby
farmers used the growth of their newly germinated autumn pastures as feed for
sheep until it was time to sow the crop. This early pasture is normally
dominated by barley grass with 5000 to 10 000 seedlings/m2 and we have found
that over 50% of roots of these plants are infected by Rhizoctonia and the
Table 1 Effect of chemical fallow on Rhizoctonia damage to wheat roots (8
weeks after sowing) and on grain yield with two tillage systems and two rotations
Tillage Rotation in year Rhizoctonia root Grain yield
preceding wheat rot ratinga (tlha)
Cultivated Peas 0.4 0.4 1.9 2,4
Volunteer pasture 1.0 1.0 2.6 2.6
Direct drill Peas 2.7 1.7 2.2 3,0
Volunteer pasture 2.9 2.1 1.2 2.2
LSD (P=0.05) Tillage 0.8 ns
Chemical fallow 0.7 0.7
Rotation ns ns
A Rhizoctonia root rot rating: ) = no disease, 5 = maximum diseade
B+ = chemical fallow (sprayed 32 days before seeding)
- = no chemicalfallow
take-all fungus. Such root material provides high inoculum sources in the
soil into which wheat is to be direct drilled. Roget et al. (1 987) developed
the concept of a short chemical fallow in which this pasture is killed with
herbicide some weeks before sowing to reduce inoculum levels; the impact of
chemical following on root damage caused by Rhizoctonia and grain yield is shown
in Table 1.
MacNish (personal communication) has not been able to reproduce the benefits of
chemical fallowing and, hence, further research is required to determine the
effects of density of grass plants, the effects of grass species, and the length
of autumn chemical following on Rhizoctonia damage.
Interaction between the herbicide chiorsulfuron and Rhizoctonia Research,
both overseas and in Australia, has demonstrated that there can be a 'downside'
to the use of certain herbicides in the presence of soilborne root diseases
caused by fungi and nematodes (Aitman and Rovira 1989). We found in both
farmers' crops and in glasshouse trials that the presence of extremely low
residues of the sulfonyl urea herbicide chiorsulfuron (Glean) led to increased
damage from Rhizoctonia to cereal roots resulting in yield losses of up to 1
t/ha (Rovira and McDonald 1986). The interactions between herbicides and root
diseases give cause for concern because of the widespread use of herbicides, but
awareness of these effects should encourage cereal growers to plant crops into
soils in which disease levels have been controlled by management strategies,
e.g. rotations for take-all and cereal cyst nematode, rotation and tillage for
Development of artificial inoculation techniques for Rhizoctonia research One
of themajor stumbling blocks in research on Rhizoctonia bare patch.had been an
inability to reproduce the 'patch' symptoms either in the field or in the
laboratory using soil from patches. When the bare patches appeared in our direct
drilled wheat plots in 1981 and we had established that these patches were due
to R. solaniAG-8 (Neate and Warcup 1985), 1 decided that it would be necessary
to develop methods by which different levels of disease could be obtained in
both glasshouse and field experiments. McDonald and Rovira (1 985) introduced
propagules of Rhizoctonia grown on sterilised white millet seed at different
rates into calcareous sandy loam, incubated for 0, 2 and 4 weeks and grew wheat
for 3 weeks at 1OOC with 8-hour days in a controlled environment cabinet. Figure
6 demonstrates that as the number of propaguies in the soil was increased, less
incubation time was needed to produce the same level of root damage.
A problem confronting research on Rhizoctonia bare patch in the field is the
uneven distribution and unpredictable location of patches. I thought that one
way of overcoming this problem would be to extend into the field the technique
Heather McDonald and I developed for pot experiments. Millet seed propagules
were broadcast over the soil surface at 300 and 1200 propaguleS/M2, incorporated
into the top
Figure 6. see Australasian Plant Pathology Vol.19 (4) 1990
Table 2 Effect of Rhizoctonia inoculum on root damage rating and wheat yield
at Avon in 1984
Number of Disease Number of Dry weightlpiantb Number of Grain yieidc
propaguies/M2 ratingAB plantSBJM (mg) heads/plant (tlha)
0 1.6 31 52 1.55 2.11
300 2.2 33 50 1.50 1.92
1200 3.1 30 41 1.36 1.74
LSD (P= 0.05) 0.6 ns 8 ns 0.23
Note: Millet seed propaguies of R. solani (McDonald and Rovira 1985) were
broadcast over the soil surface and rotovated through the top 10 cm; wheat was
direct drilled into the soil with the SIRODRILL 4 weeks later.
A Disease rating for Rhizoctonia damage: 0 = no damage, 5 = maximum damage
B 8 weeks after planting
c At maturity
5 cm with a rotary hoe, allowed to stand for 4 weeks before direct drilling
wheat with the SIRODRILL. Table 2 shows that although there was a significant
background of Rhizoctonia in this soil, the disease level could be increased and
the grain yield decreased by this method. The disease level on the roots was
uniform over the whole of the treated area, which indicated that this technique
may reduce the problem of variation in disease levels and patches in the field.
Neate (1989) has used this technique in field trials to screen cereal cultivars
for resistance to Rhizoctonia; he has also used the technique to screen
fungicides as control agents (Neate, personal communication). We have used the
technique to demonstrate the effects of Rhizoctonia on medic, ryegrass, peas and
oats (Rovira and Neate, unpublished).
Cereal cyst nematode
In their review on the impact of CCN on wheat production and the development of
integrated control methods, Rovira and Simon (1982) discussed various control
strategies e.g. chemical control, time of sowing, cultivation and rotation with
non-hosts and resistant cultivars, and their effects on crop yields. The effects
of rotation on CCN were demonstrated by Meagher and Rooney (1966) and Meagher
and Brown (1974).
Effect of soil temperature on CCN damage The relationship between CCN levels
in soil and damage to crops is confounded by a number of factors including time
of sowing. Many farmers know that they can overcome a CCN problem by sowing in
early to mid-May. Simulating different seasonal conditions in controlled
environment cabinets I demonstrated how a soil with 10 eggs/g could give root
damage ratings over the range 1 to 4 depending upon temperatures before and
after planting. Table 3 and Figure 7 demonstrate that with a simulated early
'break' and early sowing (soil kept moist at 2OoC before sowing and at 15oC for
4 weeks after sowing) ten eggs/g reduced total root length by 14%, whereas with
the simulated late break (soil kept moist at 15o before sowing) with late
sowing, viz. equivalent to early June (soil kept at 1OoC for 4 weeks after
sowing) the reduction in root growth by CCN was 81%. In these experiments, the
direct effect of soil temperature on root growth in the absence of CCN damage to
the roots was assessed from pots to which a nematicide (aldicarb) was added at
Figure 7 see Australasian Plant Pathology Vol.19 (4) 1990
SIRONEM soil bioassay for CCN When we commenced our research on CCN the
standard methods in Australia of estimating eelworm levels in soil, or damage on
plants was to count either the numbers of eggs in soil or the numbers of 'white
cysts' (immature females) on root systems at anthesis. This has its limitations,
e.g. specialist knowledge and equipment is required for egg counts in soil and
as a routine procedure egg counting is tedious and time-consuming, whilst
counting 'white cysts' reflects the population build up on roots rather than
actual damage to roots by CCN. For this reason we
Figure 3 Effect of soil temperaturesbefore and after planting on damage to
wheat roots by Heterodera avenae
Soil temperature after wetting and
before planting (OC) 20A 15A 15A
Time soil was wet
before planting (weeks) 4 2 4
after planting (OC) 15B 15 B 10 B
Total length of primary
root axes/plant (cm) 37(46)c 26(38) 27(57) NS
Total length of lateral
roots/plant (cm) 582(671) 417(815) 112(403) 153
Root damage ratingd 1.0 2.5 4.0 0.5
Dry weight tops/plant (mg) 59(86) 52(77) 29(45) 13
A Equivalent seasonal conditions:
2OOC for 4 weeks, 15OC after planting - early break in season (rains), early
15OC for 2 weeks, 15OC after planting - mid break, early seeding;
15OC for 4 weeks, 1OOC after planting - late break, late seeding.
B Plants grown at indicated temperature for 4 weeks.
C Figures in brackets obtained when aidicarb at 10 mg/kg was mixed through soil
before planting to control H. avenae.
D Root damage rating: 0 = no damage, 5 = maximum damage.
Table 4 Control of Heterodera avenae with in-furrow applications of low rates
of Counter (terbufos), Temik (aldicarb), Vydate (oxamyi), Furadan (carbofuran),
Beniate (benomyl) and Nemadi (liquid ethylene dibromide) at Calomba, South
Australia, in 1980
Chemical Rate Disease ratinga No. of Grain yield
(kg a.i.lha) on roots 'white cysts'13 (tlha)
Nil 4.4 85 0.96
Temik Gc 2.0 0.5* * ll** 2.00 * *
Counter G 0.4 2.9** 45** 1.33**
Counter G 0.6 1.9* * 27** 1.46**
Vydate SD 0.125 2.3** 59** 1.34**
Vydate SD 0.250 1.1 * * 37** 1.61 * *
Furadan SD 0.5 2.2 * * 45** 1.43* *
Nemadi L 7.4 2.6 * * 34** 1.46* *
Benlate P 0,5 2.6 * * 48** 1.25*
A Disease rating: 0 = no damage, 5 = maximum damage
B 'white cysts' = immature females
C G = granules, L = liquid, SD = seed dressing, P = powder.
*, * * Significantly different from 'Nil' treatment at P = 0.05 and 0.01 ,
developed the root damage rating scale od 0 to 5 for seedlings between 6-8
weeks after sowing; this rating system has been used as part of the soil
bioassay technique (Simon 1980). An essential element of this bioassay was
incubate the soil at a low temperature (150C) to pomote hatching (Banyer and
Fisher 1971) and then grow plants at a low temperature (100C) to exacerbate root
damage. This SIRONEM bioassay is available as a commercial soil test and is used
by many farmers and advisers. One disadvantage of the SIRONEM bioassay is that a
rating of 5 is caused by 20 or more eggs/g, so that in soils with very high CCN
populations the application of strategies to reduce CCN, e.g. rotation or
resistant cereals, may not be reflected immediately by a fall in the rating
despite a decline in egg levels. Nevertheless, the bioassay is being used by
many farmers to monitor trends in CCN levels in individual paddocks as part of
their strategy to control this disease.
Chemical control of CCN Following the successful demonstration by Brown
(1973) that low rates of aldicarb (Temik) applied in furrow at sowing controlled
CCN and increased yields, we worked with Union Carbide, ICI, DuPont, Cyanamid
and AgChem to test a range of chemicals for the economic control of CCN. Some of
the results obtained over three years are reported in Table 4.
Effect of CCN resistant cereals on the carry-over of CCN Chemical control of
CCN demonstrated the large yield losses caused by CCN in Victoria and South
Australia and promoted the interest of cereal breeders in developing resistant
cultivars. When we were conducting trials on chemical control of CCN the only
commercial cereals known to be resistant were Avon and Swan oats (Cook 1974;
O'Brien and Fisher 1974) and Festiguay wheat (McLeod 1976).
McLeod's report on Festiguay went unnoticed until this cultivar was grown around
the perimeters of wheat fields in South Australia because of its resistance to
stem rust following the rust epidemic of 1973 which severely affected local
wheat cultivars. Mr Trevor Dillon of the South Australian Department of
Agriculture and I observed that in fields where Festiguay had been grown around
the perimeters, with other wheat cultivars in the centres and then 2 or 3 years
later a CCN susceptible cultivar grown over the whole field, there was less CCN
damage and better growth of wheat where the Festiguay had been grown. The
results from two such fields are presented in Table 5.
The breeding by Sparrow, Fisher and Dube' at the Waite Agricultural Research
Institute and South Australian Department of Agriculture of the resistant
barley, Galleon, has been of tremendous value in controlling CCN in South
Australia. This is illustrated in Figure 8 from a field sown in two halves in
1983 with two barley cultivars, Weeah which is CCN susceptible and Galleon which
is resistant; after annual pasture in 1984 and 1985, the field was sown to a
single cultivar of susceptible wheat. The results also demonstrate how soil type
affects both the damage of CCN to roots and yield loss from CCN.
Effect of tillage on CCN Unexpected benefits of direct drilling which we have
found in our trials include the reduction of root damage by CCN, the lower
numbers of white females (and hence less carryover of cysts and eggs into
following seasons) and increased yields with direct drilled wheat compared with
wheat sown following cultivation (Table 6). Subsequent field experiments have
demonstrated that the higher damage from CCN with cultivation is probably due to
the mixing and spreading of cysts and hatched nematodes during cultivation
and/or the lower soil bulk density facilitating the movement of nematodes
towards the roots.
This result has been confirmed in a number of trials conducted at different
locations and also in tillage trials conducted at Roseworthy College and by the
South Australian Department of Agriculture.
Figure 8. see Australasian Plant Pathology Vol. 19 (4) 1990
Table 5 Yields of wheat in 1978 in fields in which wheats resistant and
susceptible to Heterodera
avenae were grown on Yorke Peninsula, South Australia in 1975
Farm Wheat cultivar Wheat cultivar A Number of Grain yield
grown in 1975 grown in 1978 white cysts' in 1978
per plant in 1978 (t/ha) -
1 Sabre (S) A Halberd 58 2.0
Festiguay (R) Halberd 2B 3.l C
2 Aidirk (S) Kite NAD 1.7
Festiguay (R) Kite NA 2.3C
Note: In the two years between wheat crops the fields had grass-Medicago spp.
A S = susceptible to Heterodera avenae
R = resistant to Heterodera avenae and grown around the perimeter of the field
B Reduced number of cysts significantly different (P=0.001)
C Increased yield significantly different (P=0.01)
D NA = not assessed
Table 6 Effects of cultivation on the damage to wheat roots by CCN, on the
numbers of 'white cysts' at anthesis and on grain yield at Calomba, South
Australia, in 1980
Tillage Disease Number of Grain yield
ratingA 'white cysts' (t/ha)
Cultivated 3.5 59 0.85
Direct drilled 1.7 23 1.23
LSD P= 0.05 0.7 29 0.27
A Disease rating: 0 = no damage,
5 = maximum damage
Biological control of CCN In England Dr Brian Kerry (1980) demonstrated that
biological control of CCN by nematophagous fungi was responsible for the decline
of CCN in fields which had been cropped with wheat for several consecutive
years. This led to similar studies in Australia by Kerry while with the CSIRO
Division of Soils Laboratory in Adelaide on a Reserve Bank Fellowship. Sterling
and Kerry (1983) demonstrated that Verticillium chlamydosporium, which
parasitises CCN females and eggs, was widespread but less numerous than in
English soils. In an attempt to manipulate the population of Verticillium in the
rhizosphere of wheat as a biocontrol agent for CCN, Kerry et al. (1984)
demonstrated that introduction of the fungus into soil reduced the numbers of
CCN by up to 80%. Different isolates of Verticillium colonised wheat roots to
different extents, indicating the potential for selecting isolates with greater
rhizosphere competence which could improve biocontrol activity. One problem with
biocontrol of CCN in Australia is that the population threshold for economic
losses from CCN is 2-5 eggs/g soil compared with 10 eggs/g soil in England.
Hence, the biological control agent has to perform more efficiently under
Australian conditions if it is to reduce yield losses from CCN.
I have presented results which indicate the philosophy which has driven my
program, viz. to conduct sound science with a strong field component so that
there are practical outcomes from the research as well as good scientific
publications. I believe that the success of this program has been demonstrated
by the widespread adoption by farmers of many of the techniques which reduce
root diseases and increase yields. The publications quoted in this paper
represent some of our scientific publications in this field indicating that it
is possible to marry the two goals which I set out to achieve in 1975.
I thank my colleagues in CSIRO who have worked so hard to make the program
succeed; their names appear in papers quoted in the publication list. I also
thank the many farmers for their input into the program. Collaboration from
colleagues in the State Departments of Agriculture and from Industry has helped
the program enormously. Finally, I am grateful for the support from the Wheat
Research Council and the SA Wheat and Barley Research Committees which has
enabled us to conduct the long-term field experiments so essential for a program
of this type.
- Aitman, J. and Rovira, A.D. (1989)-Herbicide-pathogen interactions in
soil-borne root diseases. Canadian Journal of Plant Pathology ll: 166-172.
- Banyer, R.J. and Fisher, J.M. (1 971)-Effect of temperature on hatching of
eggs of Heterodera avenae. Nematologica 17: 519-534.
- Brown, R.H. (1973)-Chemical control of the cereal cyst nematode (Heterodera
avenae)-A comparison of methods and rates of application of two systemic
nematicides. Australian Journal of ExperimentalAgriculture and Animal
Husbandry 13: 587~592.
- Brown, R.H. (1987)-Control strategies in low-value crops. I n Pilnciples
and Practices of Nematode Control in Crops (Eds R.H. Brown and B.R. Kerry),
pp. 351-388. Academic Press: Sydney.
- Brown, R.H. (1991)-Cereal cyst nematode. In Soil-borne Diseases of Wheat
in the Australian Environment (Ed L.W. Burgess). Oxford University Press:
Sydney. (in press)
- Cook, R. (1974)-Nature and inheritance of nematode resistance in cereals.
Journal of Nematology 6: 165-174.
- Cook, R.J. and Rovira, A.D. (1 976)-The role of bacteria in the biological
control of Gaeumannomyces graminis by suppressive soils. Soil Biology and
Biochemistry 8: 269-274.
- French, R.J. and Schultz, J.E. (1984)-Water use efficiency in a
Mediterranean-type environment. 11. Some limitations to efficiency.
Australian Journal of Agricultural Research 35: 743-764.
- Kerry, B. R. (1 980)-Biocontrol: Fungal parasites of femal cyst nematodes.
Journal of Nematology 12: 253-259.
- Kerry, B.R., Simon, A. and Rovira, A.D. (1984)-Observations on the
introduction of Verticillium chiamydosporium and other parasitic fungi into
soil for control of the cereal cyst nematode Heterodera avenae. Annals of
Applied Biology 105: 505-516.
- King, P.M., Rovira, A.D., Brisbane, P.G., Simon, A. and Brown, R.H.
(1982)-Population estimates of cereal cyst nematode and response of wheat to
granular nematicides. Australian Journal of Experimental Agriculture and
Animal Husbandry 22: 209-220.
- MacNisti, G.C. (1985). Methods of reducing Rhizoctonia patch of cereals in
Westerh Australia. Plant Pathology 34: 175-181.
- MacNish, G.C. and Neate, S.M. (1991)-Rhizoctonia bare patch, root rot and
stem lesion. In Soil-borne Diseases of Wheat in the Australian Enviroment
(Ed L.W. Burgess) Oxford University Press: Sydney. (in press)
- McAipine, D. (1 902)-Take-all in wheat. Victorian Joumal of Agriculture 1:
- McAlpine, D. (1 904)-Take-all and white heads in wheat. Victorian Joumal
of Agriculture 2: 409-426.
- McDonald, H.J. and Rovira, A.D. (1 985)-Development of inoculation
techniques for Rhizoctonia solani and its application to screening cereal
cultivars for resistance. In Ecology and Management of Soil-bome Plant
Pathogens (Eds C.A. Parker, A.D. Rovira, K.J. Moore, P.T.W. Wong and J.F.
Koiimorgen). pp. 174-176. American Phytopathological Society: St Paul, USA.
- McLeod, R.W. (1 976)-Sources of resistance to Heterodera avenae Woll. in
New South Wales. Proceedings of the Linnean Society, N.S.W 100: 195-201.
- Meagher,J.W. andbrown, R.H. (1974)-Microplotexperiments on the effect of
plant hosts on populations of cereal cyst nematode (Heterodera avenae) and
on the subsequent yield of wheat. Nematologica 20: 337-346.
- Meagher, J.W. and Rooney, D. (1 966)-The effect of crop rotations in the
Victorian Wimmera on the cereal cyst nematode (Heterodera avenae), nitrogen
fertility and wheat yield. Australian Journal of Experimental Agriculture
and Animal Husbandry 6: 425-431.
Meagher, J.W., Brown, R.W. and Rovira, A.D. (1978)The effects of cereal cyst
nematode (Heterodera avenae) and Rhizoctonia solani on the growth and yield
of wheat. Australian Journal of Agricultural Research 29: 1127-1137.
- Neate, S.M. (1 987)-Plant debris in soil as a source of inoculum of
Rhizoctonias in wheat. Transactions of the British Mycological Society 88:
- Neate, S.M. (1 989)-A comparison of controlled environment and field
trials for detection of resistance in cereal cultivars to root rot caused by
Rhizoctonia solani. Plant Pathology 38: 494-501.
- Neate, S.M. and Warcup, J.H. (1 985)-Anastomosis groupings of some
isolates of Thanatephorus cucumeris from agricultural soils in South
Australia. Transactions of the British Mycological Society 85: 615-620.
- Northcote, K.H., Hubble, G.D., lsbell, R.F., Thompson, D. H. and Bettenay,
E. (1 975)-A Description of Australian Soils. CSIRO: Melbourne.
- O'Brien, P.C. and Fisher, J.M. (1974). Resistance within wheat, barley and
oat cultivars to Heterodera avenae in South Australia. Australian Joumal of
Agriculture and Animal Husbandry 14: 399-404.
- Roget, D.K. and Rovira, A.D. (1991)-The relationships between incidence of
infection by Gaeumannomyces graminis var. tritici, rainfall and yield of
wheat in South Australia. Australian Journal of Experimental Agriculture.
- Roget, D.K., Venn, N.R. and Rovira, A.D. (1987)Reduction of Rhizoctonia
root rot of direct drilled wheat by short-term chemical fallow. Australian
Joumal of Experimental Agriculture 27: 425-430.
- Rovira, A.D. (1985)-Manipulation of the rhizosphere microflora to increase
plant production. In: Reviews of Rural Science: No. 6. Biotechnology and
Recombinant DNA Technology in the Animal Production Industries. (Eds R.A.
Leng, J.S.F. Barker, D.B. Adams and K.J. Hutchinson) pp. 185-197. University
of New England: Armidale.
- Rovira, A.D. (1 986)-Influence of crop rotation and tillage on Rhizoctonia
bare patch of wheat. Phytopathology 76: 669-673.
- Rovira, A.D. (1990)-Sustainability of modern cereallivestock farming
systems in Southern Australia. In: Proceedings of the 5th Australian Soil
Conservation Conference. (in press)
- Rovira, A.D., Brisbane, P.G., Simon, A., Whitehead, D.G.
and Correll, R.L. (1981)-Influence of cereal cyst nema- S
tode (Heterodera avenae) on wheat yields in South Australia. Australian
Journal of Agriculture and Animal Husbandry 211: 516-523.
- Rovira, A.D. and Campbell, R. (1975)-A scanning electron microscope study
of interactions between microorganisms and Gaeumannomyces graminis (syn.
Ophiobolus graminis) on wheat roots. Microbial Ecology 2: 177-185.
- Rovira, A.D., Koiimorgen, J.F., MacNish, G.C., Sivasithamparam, K. and
Wong, P.T.W. (1 991)-Take-all. In: Soilbome Diseases of Wheat in the
Australian Environment (Ed L.W. Burgess) Oxford University Press, Sydney.
- Rovira, A.D. and McDonald, H.J. (1 986)-The effect of the herbicide
chiorsuifuron, on Rhizoctonia bare patch and Take-all of barley and wheat.
Plant Disease 70: 879-882.
- Rovira, A.D. and Ridge, E.H. (1979)-The effect of methyl bromide and
chioropicrin on some chemical and biological properties of soil and on the
growth and nutrition of wheat. In: Soil Disinfestation, (Ed D. Mulder) pp.
231-250. Elsevier: Amsterdam.
- Rovira, A.D., Roget, D.K., Neate, S.M., Smettem, K.R.J., Fitzpatrick, R.W.,
McKenzie, N.J., Buckerfield, J.C. and Simon, R. (1990)-The effect of
conservation tillage practices on soil properties, earthworks, cereal root
diseases and wheat yields. In: Proceedings of the 5th Australian Soil
Conservation Conference. (in press)
- Rovira, A.D. and Simon, A. (1982)-Integrated control of Heterodera avenae.
European Plant Protection Organization Bulletin 12: 517-523.
- Rovira, A.D. and Simon, A. (1985)-Growth, nutrition and yield of wheat in
calcareous sandy loams of South Australia. Effects of soil fumigation,
nematicide and nitrogen fertilisers. Soil Biology and Biochemistry 17:
- Rovira, A.D. and Wildermuth, G.B. (1 981)-The nature and mechanisms of
suppression. In: Biology and Control of Take-all (Eds P.J. Shipton and M.J.C.
Asher) pp. 385-415. Academic Press: London.
- Samuel, G. and Garrett, S.D. (1 932)-Rhizoctonia solani on cereals in
South Australia. Phytopathology 10: 827-836.
- Simon, A. (1 980)-A plant assay of soil to assess potential damage to
wheat by Heterodera avenae. Plant Disease 64: 917-919.
- Simon, A. and Rovira, A.D. (1985)-New inoculation technique for
Gaeumannomyces graminis var. tritici to measure dose response and resistance
in wheat to field experiments. In: Ecology and Management of Soil-bome Plant
Pathogens (Eds C.A. Parker, A.D. Rovira, K.J. Moore, P.T.W. Wong and J.F.
Koiimorgen) pp. 183-184. Amerir,an Phytopathological Society: St Paul, USA.
- Simon, A., Rovira, A.D. and Foster, R.C. (1987)-Inocula of Geeumennomyces
graminis var. tritici for field and giasshouse studies. Soil Biology and
Biochemistry 1 9: 363-370.
- Smiley, R.W. (1 978a)-Antagonists of Gaeumennomyces graminis from the
rhizoplane of wheat in soils fertilized with ammonium or nitrate nitrogen.
SoiiBiologyandBiochemistry 10: 169-174.
- Smiley, R.W. (1978b),-Colonization of wheat roots by Gaeumannomyces
graminis inhibited by specific soils, micro-organisms and ammonium-nitrogen.
Soil Biology and Biochemistry 10: 175-179.
- Stirling, G.R. and Kerry, B.R. (1983)-Antagonists of the cereal cyst
nematode, Heterodera avenae Woll. in Australian soils. Australian Journal of
Experimental Agriculture and Animal Husbandry 23: 318-324.
- Venn, N.R., Whitehead, D.A.R.G. and Swaby, B.A. (1982)-Description of the
SIRODRILL direct drill seeder. CSIRO Division of Soils Technical Memorandum
- Wildermuth, G.B., Warcup, J.H. and Rovira, A.D. (1 979)Mechanism and site
of supression of Gaeumannomyces graminis var. tilfici in soil. In: Soil-Bome
Plant Pathogens (Eds B. Schippers and W. Gams) pp. 158-164. Academic Press: