EDITOR’S COMMENTS BY SEAN MILLER, PAG, INTEGRATED PEST MANAGEMENT AGROLOGIST
Harvest of winter cereals and pulses has begun in some regions of the province. For
more information on the progress of the 2012 crop, consult the Saskatchewan Ministry
of Agriculture’s Weekly Crop Report at: www.agriculture.gov.sk.ca/Crop-Report
At this time of year, it is easy to get caught up in preparations for harvest. Nonetheless,
whether you are a farmer, researcher or agronomist, it is important to continue
monitoring fields whenever possible and to record the latest crop conditions, weather
and pest observations from this season. Making notes on the problems that came up
this year and how they were solved will help us be ready to predict issues before they
arise next time.
If you are applying a crop protection product this time of year, please remember to
follow the pre-harvest interval guidelines. Refer to the crop protection product label or
the product information in the 2012 Guide to Crop Protection
(www.agriculture.gov.sk.ca/Guide_to_Crop_Protection) for more information on a
specific product’s pre-harvest interval.
Pre-harvest glyphosate should not be applied to crops destined for planting seed, as
the germination and vigour levels can be negatively affected.
Crop Production News VOLUME 34 NO. 6
AUGUST 3, 2012
Crop Production News is a bi-weekly publication prepared primarily by provincial
specialists with the Crops and Regional Services branches of the Saskatchewan
Ministry of Agriculture. It is a compilation of articles related to entomology, plant pathology, weed science, soils and
agronomy issues.
Please do not use any of these articles for any other purpose without first asking the
author’s permission.
If you wish to be added to or removed from our mailing list, forward your request by
email to: [email protected]
IN THIS ISSUE
Aster Yellows on the Increase
This Year ………………………………. 2
Looks Like Another Sclerotinia
Year ……………………………………. 3
Planning Winter Wheat This Fall:
Some Nutrient Tips to Consider ….… 5
Swede Midge and Other Insects
in Canola in 2012 …………………..... 5
Crop Protection Lab News ………….. 7
White Heads in Wheat? ……………... 7
Crop Questions of the Week ……...… 9
ASTER YELLOWS ON THE
INCREASE THIS YEAR BY ALICA OLSON, SUMMER STUDENT, NORTH BATTLEFORD REGIONAL SERVICES BRANCH
If you see plants in your field that look different or
that seem to be growing abnormally, take a closer
look as it may be aster yellows. With the
combination of a wet spring, recent hot weather and
an abundance of leafhoppers earlier on, there has
been an increase in the incidence and the symptoms
of aster yellows in many areas.
Aster yellows is a disease caused by a
pathenogenic micro-organism called a phytoplasma.
The symptoms of the disease depend on the
species of plant. The most obvious symptoms are
the malformed flowers and pods that give the plant
an abnormal appearance (Figure 1). Aster yellows
can affect 300 species of plants in 48 plant families,
including broadleaf crops, vegetables, ornamentals,
weeds and, to a lesser extent, cereal crops. In
Saskatchewan, the crops that we may see
symptoms on include canola, camelina, mustard,
flax, sunflower, alfalfa, potato, carrot, tomato, pea,
wheat and barley. You may also see various weeds
infected with aster yellows, including redroot
pigweed, dandelion, stinkweed, chickweed,
quackgrass, wild mustard, lambsquarters, knotweed
and sowthistle.
The phytoplasma pathogen lives in the phloem
tissue or the sap of infected plants and is transmitted
from plant to plant by leafhoppers. Another source of
the pathogen is the United States where it can be
carried by infected leafhoppers arriving on wind
currents. Leafhoppers acquire the phytoplasma and
transmit it to new plants as they feed. They insert
their needle-like mouth parts into plant tissue, inject
their saliva, then suck up the sap. It is through their
saliva that the aster yellows phytoplasma is
transmitted. Leafhoppers do feed on the plant but
the feeding itself is not considered an economic
threat to the crop; it is the disease transmission that
is a concern.
After feeding on an infected plant, it takes two to
three weeks before the leafhopper becomes
infectious and can pass it on to other plants. The
infectious period will last for the remainder of the
leafhopper’s adult life (one to three months) during
which the infected hopper can move from field to
field spreading aster yellows. Luckily, the
phytoplasma is not transmitted to the overwintering
eggs; however, the pathogen can overwinter in the
root tissue of biennial or perennial crops or weeds,
thereby providing a source of the disease in early
spring.
Once infected, symptom development depends on
the age of the plant. Younger plants show symptoms
within several days, while older plants can take two
to four weeks. Because of the delayed expression of
the disease in plants, symptoms usually appear later
in the season and damage is minimal. In 2007, aster
yellow was more prevalent and some Prairie canola
fields had up to 15 per cent infected plants. Potential
yield loss is hard to determine, as it depends on the
level of infection and how early the plant was
infected; however, research by Agriculture and Agri-
Food Canada in Saskatoon has shown that a 10-
per-cent incidence of infected plants may result in
yield losses of between three and seven per cent.
Symptoms on the plant can vary from completely
abnormal looking plants to more normal looking
plants that have reduced seed set. Some plants can
Figure 1: Aster yellows on canola
Source: Saskatchewan Agriculture
2
look normal but the pods are empty. Unfortunately,
these symptoms do not appear until late in the
season. In most years, fields will only show trace
amounts of this disease (rarely more than five per
cent). Usually, economic loss from aster yellows in
canola is minimal. In canola, the damage usually
looks worse than it actually is, because infected
plants are usually taller than the rest of the crop,
with distinctive symptoms and an erect nature.
Infected canola plants are often discoloured, with
flowers replaced by green leaf-like structures and
pods becoming deformed and bladder-like in
appearance.
We have had reports of aster yellows in fields in
Saskatchewan. This is not surprising, given that
leafhoppers were reported in high numbers this
spring with a higher-than-average infection rate
reported by Agriculture and Agri-Food Canada.
Unfortunately, there is nothing to fix the situation.
There are no products registered to control the
disease itself and no varieties with resistance. Once
the symptoms appear, there is nothing that can be
done to reverse the infection or kill the organism.
Ways to minimize the potential for aster yellow
infection in future years include: seed early, control
perennial weeds in and around susceptible crops,
avoid planting near perennial crops that are known
to be infected, and watch for the presence of leaf
hoppers. Application of an insecticide registered for
use on leafhoppers may be beneficial if populations
are high enough early in the season.
For more information contact your nearest regional
crops specialist or the Agriculture Knowledge Centre
in Moose Jaw at 1-866-457-2377.
LOOKS LIKE ANOTHER
“SCLEROTINIA YEAR” BY FAYE DOKKEN-BOUCHARD, PAG PROVINCIAL SPECIALIST, PLANT DISEASE
Sclerotinia sclerotiorum is a fungus that affects
broadleaf crops. It is favoured by moist conditions,
so, given Saskatchewan’s relatively dry climate, we
do not experience widespread infection every year.
Similar to 2010, it appears that 2012 will be another
“sclerotinia year” thanks to excess rainfall, thick crop
canopies and readily available sources of inoculum.
In 2010, the average incidence of sclerotinia white
mould in canola was 20 per cent (with incidence up
to 93 per cent). In 2011, the provincial average
dropped to 10 per cent but there were still crops with
up to 92 per cent incidence of sclerotinia white
mould reported in the survey, reflecting the potential
difference in any given field compared to the
provincial norm.
Numerous cases of sclerotinia-infected crops have
already been reported throughout much of the
province in 2012, and infestations in canola, lentil,
pea, chickpea, sunflower and various vegetable
crops is possible. Disease surveys will take place in
August but, based on preliminary reports, it is
expected that sclerotina white mould will be severe
in some fields.
In canola, the disease cycle begins with flower petal
infection. Ascospores released by apothecia (Figure
2) infect flower petals, which are easier to penetrate
than other plant parts. The fungus then uses flower
nutrients to grow strong enough to infect other
tissues after petals drop. Fallen petals are
sometimes trapped in the crux of a branch, a moist
spot where infection can occur. Figure 3 shows early
symptoms of sclerotinia developing in the crux of a
canola branch.
In pulses, particularly lentils (Figure 4), infection can
occur through direct contact with mycelium produced
by the sclerotia in the soil. The fungus then spreads
Figure 2: Sclerotinia apothecia
Source: Saskatchewan Agricultue
3
through plant-to-plant contact, which is facilitated by
thick, lodging crops.
Regardless of the method of infection, moisture is
the key to sclerotinia white mould development,
making the disease as difficult to forecast as the
weather. Infections tend to occur below the crop
canopy: a humid, windless microclimate highly
suitable for disease development. Infection of the
plant stem adversely affects nutrient and moisture
flow within the vascular tissue of the plant. This
results in premature death of the plant or reduced
yields. Eventually, sclerotia will form on or inside the
plant and drop into the soil before or during harvest,
and thus are available to cause disease in the
future. Rotation away from susceptible crops is
required to prevent infection; however, this is not
usually an option due to the long life of the resistant
sclerotia (up to five years) and the agronomic
requirement for diversity in our crop rotation
(including broadleaf crops).
In order to control this disease, fungicides need to
be applied early. The most opportune time to apply
fungicide is between 20 to 50 per cent bloom for
canola. The earlier the disease causes infection, the
more time it has to cause damage. Therefore later
infections will cause less damage, making control
less economically beneficial. With pulses, timing is
more difficult, as the start of flowering is the
recommended fungicide target for management of
pulse diseases and sclerotinia doesn’t usually
appear until after the canopy closes. Completion of
flowering and closure of the crop canopy effectively
limits the impact fungicide might have on the
situation, as the product cannot be applied to the
parts of the plant most heavily affected by the
disease. Sclerotinia is a mono-cyclic disease, which
means there is only one disease cycle per season. If
you do not stop it before the disease cycle has
reached the point of producing visible symptoms, it
is too late to control. Economic gains are not
realized if fungicide is applied too late, and there is
no agronomic benefit.
Fungicides are made to protect the plant, not cure
disease. Keep in mind that fungicides’ so-called
systemic effect usually refers to the chemical’s ability
to move into the immediate cell structure of the
plant. The chemicals are not carried through
vascular tissue to reach all parts of the plant;
therefore, their effectiveness is based on contact
with the immediate zone of concern.
For more information on this disease, see the
Saskatchewan Agriculture factsheets Sclerotinia
Infection in Field Crops and Sclerotinia Rot of
Vegetables.
Figure 3: Sclerotinia lesion forming in the crux of a canola
branch
Source: Saskatchewan Agriculture
Figure 4: Sclerotinia white mould growing on lentil pods
Source: Saskatchewan Agriculture
4
PLANNING WINTER WHEAT THIS
FALL: SOME NUTRIENT TIPS TO
CONSIDER BY KEN PANCHUK, PAG, PROVINCIAL SPECIALIST, SOILS
The focus, when establishing winter cereals, is to
seed shallowly into a field of standing stubble at the
correct seeding date. Ideally, winter wheat should be
seeded by the end of August in the northern part of
the province and by the end of the second week of
September in the south. Also, leaving as much
stubble as possible standing after seeding will trap
snow and provide an early insulating blanket as well
as conserving moisture.
Starter phosphate fertilizer with perhaps some
potash blended in assists in achieving healthy plants
for optimizing the winter hardiness going into winter,
as well as improves winter survival.
What are the nitrogen options? A soil test prior to
seeding will indicate the level of nitrogen left from
the previous crop and assist in determining how
much phosphate and potash is needed.
When considering nitrogen options, look at field
conditions too. If it is wetter than normal when you
are seeding winter wheat, you may want to use
ESN, a polycoated urea to minimize nitrogen losses
during the fall and the spring melt. If conditions are
normal, then urea in a side-band or mid-row-band
will work well. Remember not to compromise the
shallow-seeding-depth requirement just to get the
fertilizer banded into the soil.
If winter survival is excellent and moisture conditions
point to potentially high yields, additional urea-
nitrogen can be broadcast in early spring with or
without a urease-inhibiting product, depending on
conditions at the time. Dribble-banding liquid
nitrogen with or without a urease-inhibiting product is
also an option for early spring application.
To discuss these and other agronomic
considerations when planning for winter wheat or
other winter cereals, contact the Agriculture
Knowledge Centre at 1-866-457-2377 or your
nearest regional crops specialist.
SWEDE MIDGE AND OTHER
INSECTS IN CANOLA IN 2012 BY SCOTT HARTLEY, PAG, PROVINCIAL
SPECIALIST, INSECT AND VERTEBRATE PEST
MANAGEMENT
AND
DR. JUDY SOROKA, RESEARCH SCIENTIST,
AGRICULTURE AND AGRI-FOOD CANADA,
SASKATOON
Swede midge larvae have been found in misshapen
canola flowers in fields in the northeast of
Saskatchewan. Canola fields in the Codette,
Nipawin and Carrot River areas surveyed on July 18
to 20 were found to contain swede midge larvae.
Symptoms included aborted flowers or flowers with
petals apparently fused or glued together, and
misshapen, stunted or sometimes missing pods.
This should not be confused with aster yellows (see
article on page 2).
The first suspected specimens of swede midge
larvae in Saskatchewan were collected west of
Nipawin in 2003, but the specimens were not
positively identified and no other larval infestations
were found until now. Canadian Food Inspection
Agency personnel caught small numbers of adult
swede midge in pheromone traps in the
northeastern (Nipawin and Melfort) and east-central
(Yorkton) areas of Saskatchewan in 2007.
Swede midge larval feeding causes swollen, twisted
and distorted plant tissue. Prior to 2012, no
symptoms of swede midge infestations were noted
in Saskatchewan canola. In Ontario, where the pest
was found in 2000, symptoms of damage associated
with swede midge depend on the growth stage of
canola, when feeding occurs and the intensity of
feeding. If larvae attack pre-bolting canola, the
growing point may become necrotic and bolting
might not occur. Damage to a bolting stem may
cause a “palm tree” effect, with a shortened raceme
crowned with a bouquet of pods radiating out from
one point rather than along a typical raceme. After
full flowering, swede midge does not impact canola
5
yields. In the northeast this year, the racemes
appeared normal except that some flowers had
fused petals that did not open. When dissected, the
flowers contained small larvae, with up to 14 found
in one flower (Figure 5). Small, misshapen or
missing pods occasionally were found below the
infested flowers.
The reasons for the outbreak in Saskatchewan in
2012 are not known. Moist conditions in 2011 and
2012 would have been favourable for swede midge
population buildup. In addition the mild winter of
2011-12 may have allowed for better over-wintering
survival of the swede midge.
Native to Eurasia, the swede midge is similar in size
to the wheat midge, with both belonging to the fly
family Cecidomyiidae. However, the swede midge
feeds only on plants in the crucifer (cabbage) family,
and differs from wheat midge in colour, being
creamy yellow rather than orange; swede midge
larvae can “jump” or spring away from contact. In
Ontario, there are four generations of swede midge
a year. Overwintering in the soil as pupae, the first
spring adults appear in mid- to late May. Effective
insecticidal control is difficult because of overlapping
and multiple generations, short adult life span and
the concealed nature of larval feeding.
Other Insect Issues
In all situations of insect infestations it is
important to use registered insecticides if
control is required and to keep in mind pre-
harvest intervals when considering control
options.
Aphid infestations have been reported in several
areas and in a variety of crops including lentil, pea,
canaryseed, wheat, barley and canola. The need for
control will depend on the number of aphids present.
insecticide must be registered for the crop. Refer to
the documents Economic Thresholds of Insect Pests
and the 2012 Guide to Crop Protection, available on
the Saskatchewan Agriculture website, for control
options.
Zebra caterpillars continue to cause damage to
podded canola fields, primarily in the southeast.
Most reports indicate the caterpillars are large and
feeding should soon cease, but if the large larvae
are actively feeding on pods, treatment may be
warranted if it is combined with other insect feeding.
See the Crop Production News July 23 issue for
more information on aphids and zebra caterpillars.
Bertha armyworm larvae are on the increase in
many areas. The final bertha armyworm map of
adult moths is posted on the Saskatchewan
Agriculture website. The map is an indication of risk
based on potential mating adult moths. Actual larval
numbers will be specific to the field. Various colour
versions of bertha larvae, including the typical darker
black types, have been observed. In most cases, the
larvae are now in later and more destructive larval
stages and control may be required. Some
infestations are well above economic thresholds.
Figure 6 shows the remnants of bertha armyworm
larvae on a wheel following insecticide application.
Refer to the
Saskatchewan
Agriculture
publications
Bertha
Armyworm or
Economic
Infestations of
Insect Pests for
recommended
economic
thresholds.
Figure 5: Swede midge in a canola floret
Source: Agriculture and Agri-Food Canada, Saskatoon
Figure 6: Remnants of bertha
armyworm larvae
Source: Saskatchewan Agriculture
6
CROP PROTECTION LAB NEWS BY CECILIA PELUOLA, AAG, SUPERVISOR, CROP PROTECTION LAB
Crop pest issues continue to emerge across the
province, which has been reflected in samples
submitted to the Crop Protection Laboratory over the
last month. Environmental and chemical damage
was diagnosed as well, and the most frequently
submitted samples included wheat, barley, canola,
lentil, pea and flax.
Diseases of cereals and grasses diagnosed in the
last month included smut caused by Ustilago tritici
on wheat and U. bullata on wheat grass. Numerous
wheat samples have been submitted recently
exhibiting white heads. We are in the process of
investigating a number of possible causes: refer to
the White Heads in Wheat article on this page for
further information.
Several barley samples have also been received
with brown glumes (Figure 7). These symptoms can
be associated with fusarium head blight, spot blotch,
and even physical damage such as hail. Lab plating
techniques can be used to differentiate any
pathogens associated with these symptoms.
Diseases diagnosed on oilseed crops such as
canola, flax and sunflower included blackleg
Leptosphaeria sp, alternaria leaf spot, sclerotinia
stem and pod rot and aster yellows.
Diseases diagnosed in peas included root rots (likely
associated with Fusarium spp), ascochyta foot rot,
mycosphaerella blight, leaf spots caused by Septoria
pisi and Ascochyta pisi, and sclerotinia stem rot.
Lentil samples have reflected the moist conditions
and thick crop canopies found in many fields this
season—with evidence of sclerotinia stem rot,
botrytis grey mould, ascochyta blight, anthracnose,
and stemphylium blight in various combinations.
Insect pests identified in the last month included leaf
gall wasp (Neuroterus sp), oak petiole gall wasp
(Andricus quercuspetiolicola), weevils (family
Curculonidae), seed bugs (family Lygaeidae), and
gall mites (Eriophyes sp).
Weed samples identified recently included Parietaria
pensylvanica (Pennsylvania pellitory), Rumex sp
(dock sp), Agrostis scabra (rough hair grass) and
Galium sp (cleavers).
WHITE HEADS IN WHEAT? BY CROPS BRANCH SPECIALISTS
Farmers and agronomists have been reporting
wheat fields with numerous white heads that have
appeared in the last couple of weeks. The Crop
Protection Lab has received many calls and samples
and is in the process of investigating a number of
possibilities.
Fusarium Head Blight and Other Disease Issues
Wheat that survives the seedling blight and root
rotting complex (Cochliobolus sativus and Fusarium
spp) at the seedling stage but succumbs after
heading may suffer from prematurity blight. Infected
plants are often scattered throughout the field. They
are easily pulled from the soil and exhibit poorly
developed and discoloured roots and crowns along
Figure 7: Six-row barley with brown glumes
Source: Saskatchewan Agriculture
7
with white heads that produce few or no kernels
(Figure 8).
Most of the Fusarium species involved in root rots
may also cause fusarium head blight (FHB) if spores
come in contact with the heads, spreading through
rain or wind during anthesis (flowering). Premature
bleaching (Figure 9) will be apparent in one or more
of the spikelets in a head, sometimes including the
rest of the spike above the point of infection. These
spikelets may not produce seed, or result in light,
chalky kernels. Pink or orange Fusarium spores are
sometimes visible on the glumes of infected plants,
particularly when conditions remain wet after
infection.
“Take-all” (Gaeumannomyces graminis) can cause
stunting, reduced tillering, empty white heads and
premature ripening or death. The disease often
occurs in patches and, similar to root rots, plants
with rotten roots are pulled easily from the ground.
Unlike root rots however, fungal growth may be
visible on the lower stem of plants infected with take
all and roots and culms may exhibit a shiny black
appearance.
Barley yellow dwarf infections may cause premature
death of infected plants, which are stunted with
yellow leaves and few tillers. Spikelets may be
sterile on the top and bottom of the spike, which is
also reduced in size.
Aster yellows has been widespread in other crops
this season (see the aster yellows article on page 2).
Wheat is commonly infected with aster yellows but
rarely shows symptoms. Previously reported rare
symptoms include yellowing leaves, shriveled heads
with distorted awns or floral parts that look like
leaves. Many of the reported white heads have been
on green stems with healthy roots and no obvious
disease symptoms (Figure 10). As a precaution,
some samples like this have been submitted for
aster yellows diagnosis. Results will be reported
when available.
Under high disease pressure from leaf spots,
glumes and awns may become spotted. Plants that
have died or ripened prematurely for any reason
may also exhibit sooty moulds which turn the heads
brown or black due to the growth of saprophytic
fungi. By the time any of the above disease issues
appear, control with a fungicide is not beneficial.
Figure 10: White heads with green stems (cause unknown)
Source: Saskatchewan Agriculture
Figure 9: Bleached spikelets caused by FHB
Source: Saskatchewan Agriculture
Figure 8: White head (photo) with stem (inset) that pulled
away easily due to root rot
Source: Saskatchewan Agriculture
8
Insects
There are insects that can cause white heads in
wheat, most commonly the wheat stem maggot
(Meromyza Americana), which is the larva of a fly.
Eggs are laid by the adult fly in the upper part of the
plant and the larva burrows in to consume the
interior parts of the stem. The upper part of the stem
dies and the result is a bleached or white head.
Although the white heads are obvious in a green
field, the actual infestation rate of wheat stem
maggot is usually only about one per cent. To
determine if it is a maggot, pull the wheat head and
stem from the sheath. If the stem pulls out easily, a
maggot is usually the culprit (Figure 10). If the stem
does not detach easily, it is usually indication of
another problem.
Wheat stem sawflies do not generally cause white
heads in wheat. The feeding of a sawfly larva can
result in reduced seed set or shriveled seed but not
mortality of a complete head.
Herbicide Damage
It is very unlikely that herbicide exposure would
result in the production of white heads in cereal
plants without other symptoms of that herbicide also
being apparent. Herbicides in Groups 1, 2, 5, 6, 7, 9,
10, 11, 14 and 27/28 have the potential to produce
bleaching symptoms, but to produce white heads,
exposure to these herbicides would have to occur
very late in the development stages of the plants; in
most cases well beyond the herbicide’s
recommended application window.
Group 4 herbicides can also result in the formation
of white heads, either directly as a result of
application outside of the recommended application
window, or indirectly as an additional stress on a
plant already predisposed to the formation of white
heads as a result of other stresses indicated in this
article. The risk of Group 4 herbicides being an
indirect contributor to the formation of white heads
increases greatly when they are applied outside of
the recommended plant stage.
Environmental Stress
High temperatures along with bright sunlight and hot
winds may cause heat sterility or stress of entire
plants or portions of the head. Heat during filling can
also cause a number of kernel conditions as well.
Plants that were stressed due to excess moisture
earlier in the season may have shallow rooting depth
and be particularly sensitive to heat stress later in
development. On the flip side, low temperatures can
also stress plants and damage immature heads.
Hail damage can also cause white heads when
death occurs above the point of injury. In this case,
wheat heads will be accompanied by signs of
physical damage (broken stems, missing glumes,
etc.).
Unfortunately, no matter what the cause of white
heads in wheat this season, nothing can be done at
this stage to resolve the issue. There may be more
than one factor at play in a given field, and while the
appearance may be alarming, the symptoms likely
appear worse than the actual damage.
CROP QUESTIONS OF THE WEEK BY BRENT FLATEN, PAG, CCA, INTEGRATED PEST MANAGEMENT SPECIALIST, AGRICULTURE KNOWLEDGE CENTRE
The most commonly asked questions this past week
included the much higher than normal incidence of
aster yellows in canola and, in some cases, flax (see
article on page 2), insect pests, crop diseases and
non-pathogenic yellowing of crops.
Many people are noticing yellowing in cereal crops
such as wheat. In most cases, these yellowed
leaves have been turning bronze as they dry down.
These characteristics can be attributed to what we
call physiological leaf spot (non-pathogenic causes),
leaf diseases
such as tan
spot and
septoria
complex, or a
combination
of both.
Figure 11
shows
physiological
leaf yellowing
with no
Figure 11: Physiological leaf spot
Source: Saskatchewan Agriculture
9
apparent disease. Figure 12 shows physiological
leaf yellowing along with leaf disease.
Loose smut is also showing up. Figure 13 shows a
wheat head after wind and rain removed most of the
black loose smut mass. Spores from smutted heads
won’t produce more smutted heads in the same
crop-year, but will infect nearby wheat, the seeds of
which will cause infection next year. Only a systemic
seed treatment that controls the loose smut hidden
inside infected seeds can control the disease.
Inquiries have also been dominated by insect issues
such as aphids in lentils, wheat, canaryseed, canola
and peas. Other canola insects, including
diamondback larvae, bertha armyworms and zebra
caterpillars, have been issues.
A final issue was the raising of Europe’s maximum
residue limit for glyphosate in harvested lentils.
Although this makes pre-harvest glyphosate
possible for lentils bound for Europe, contact your
buyers to make sure they will accept lentils that have
had pre-harvest glyphosate applied.
When applying later-season fungicides and
insecticides, always take into account the pre-
harvest intervals requires so that crops do not
exceed maximum residue limits. Remember that
“pre-harvest” means before the crop is cut (either
swathed or straight-combined). Pre-harvest intervals
do not include the time the crop is in the swath.
The Crop Production News is a publication of
Crops Branch, Saskatchewan Ministry of Agriculture
Telephone: (306) 787-4671
Email: [email protected]
Figure 13: Loose smut head after wind and rain
Source: Saskatchewan Agriculture
Figure 12: Leaf disease and physiological leaf spot
Source: Saskatchewan Agriculture
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