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MANAGEMENT GUIDE
THE
WEEVILPEA LEAF
Introduction
Pea leaf weevil management starts hereThe pea leaf weevil (Sitona lineatus) is an invasive pest that poses an increasing threat to field pea and faba bean production in Western Canada. The insect can cause damage at multiple stages of the life cycle, leading to significantly reduced yields.
Use this guide to help you correctly identify, scout and manage this damaging insect in your pulse crops. With the agronomic tips and actionable management strategies found in the pages ahead, you’ll be well equipped to make informed decisions about protecting your pea and faba bean crops.
Contents
WHA
T’S
IN T
HIS
GUID
E?The Pea Leaf Weevil Management GuideIdentification 5
Life cycle 6
Outbreak factors 7
Affected areas 8
What’s at stake? 10
Management practices 11
Scouting 13
Cruiser Maxx® Vibrance® Pulses seed treatment 15
Matador® insecticide 19
Voliam Xpress® insecticide 21
PEA
LEAF
WEE
VILS
Pea Leaf Weevil Management Guide 5
IdentificationAdult
Adult pea leaf weevils are slender, greyish- brown beetles about 5 mm long with a broad-shaped snout. Three light-coloured stripes extend length- wise down the thorax and sometimes the abdomen.
Larvae
Pea leaf weevil larvae are C-shaped and measure about 3 to 6 mm in length. The legless larvae are soft-bodied and milky white with a dark brown head.
Pea Leaf Weevil Management Guide 6
Life cycleThe pea leaf weevil produces one generation per year and develops through four life stages: egg, larvae, pupae and adult.1,2
Season Life cycle
Winter Adults overwinter in alfalfa or other perennial legume crops, ditches and shelterbelts.
Late April– to early May
Adults emerge from their winter habitat and begin feeding on available leguminous greens.
May to June Adults walk or fly (at temperatures above 17°C) to legume fields to reproduce. Females lay up to 1,500 eggs in the soil near developing plants. Eggs are small, smooth and oblong. They are white when laid, but turn nearly black at hatching.
July Larvae feed on pulse crop nodules and grow through five instar stages, then burrow into the soil and pupate.
August Adults emerge and feed on pea crops.
Late summer to fall
Adult weevils fly and migrate to their overwintering sites.
Sources: 1.“Pea Leaf Weevil,” Agri-Facts, Alberta Agriculture, 20142. “Pea Leaf Weevil,” Pest Fact Sheet, Montana State University, 2016
Pea Leaf Weevil Management Guide 7
Outbreak factorsSpring weather conditions have a significant effect on the timing and severity of pea leaf weevil damage.1,2
Outbreak factor Result
Temperature Pea leaf weevils will arrive in fields early if warm conditions (above 20°C) persist for more than a few days in late April or early May, resulting in higher yield loss. In years when cool weather persists, the arrival of pea leaf weevils can be much later, and the yield impact less serious.
Moisture Dry years make plants more susceptible to the pea leaf weevil. In wetter years there is more nitrogen available to the plant, making it less susceptible to the pest.
Sources: 1.“Pea Leaf Weevil,” Agri-Facts, Alberta Agriculture, 20142.“Pea Leaf Weevil,” Grainews, May 17, 2016
Pea Leaf Weevil Management Guide 8
Affected areasFirst spotted in Alberta in 2000, pea leaf weevil is now a serious pest in southern Alberta and southern Saskatchewan. In recent years it has been sighted as far north as Athabasca, Alberta.
The map below displays the incidence of pea leaf weevil in 2018, as monitored by the government of Alberta. Officials advise that central Alberta is a transitional area where pea leaf weevil incidence has worsened in recent years.
Pea leaf weevil in Alberta - 2018
Source: Alberta Agriculture, Food and Rural Development, 2018
Edmonton Lloydminster
Red Deer
Calgary
Lethbridge
Medicine Hat
>0 – 1 >1 – 3 >3 – 9>9 – 27>27
0
Average notches per plant
Average notches per plant
0 – 1 >1 – 3 >3 – 9>9 – 27>27
While pea leaf weevil populations were low in 2018, the pest’s overall spread and intensity have been on the rise for several years. Alberta Agriculture and Forestry specialist Scott Meers cautions against interpreting low presence as a reduced need to apply seed treatment, as populations have been known to rebound quickly.
Pea Leaf Weevil Management Guide 9
Affected areasPea leaf weevil has been expanding to the north and east in Saskatchewan the past several years.
KindersleyOutlook Watrous
Humboldt
Melfort Tisdale
Estevan
Melville
Weyburn
Moose Jaw
Regina
Prince Albert
Lloydminster
Saskatoon
Swift Current
North Battleford
Meadow Lake
Yorkton
142
410
288
167
46
75
104 103
134
164165
135
105
316
283
194
225
256
1011
102 101
340
490
37
8 7
38
368
307
367
35
245
304
333 331
169
40 39
66
318
232
273
107
337
282 280 275
70
435
305
464
310
398
108
131
319
128
335
166
7379
312
152
92 91
487
456
138141
274
127
372
230
36
260
351
106
281
224 215
284
315
491
397
122
469
313
42
286287
317
2
9798
346
18
371
334
6
381
411
76
96
7172
132
121
6874
99
129
279
69
226
369
34
246
151
121
217 214 213
19
4933
338339
3132
321 320
257
229
440
253254
61
252
349
185
488
376
4
78
467
168
163
133
401
130
341342
136
350
380
219
123
171
110
125126
183
153
404
429
186
109
139
460
187
502
434
458
63
428
157
322309
64
51
124
17
400
155156
241
498
193
223
402
436
459
497
303
292
336
276
430
222
379
520
184
394
100
248
377
472
442
4443
162
501
45
471
555
494
154
216
190
468
191
345
366
395
314
218
486
93
588
9
403
439
231
9495
244261
137
437
111
561
399
622
211
181
457
373
427
344
277
247
271
259
228
77
382
352
521
406
158
405
250251
470
370
426
255
308
499
343
65
496
3
189
243
466
160
301
409
438
221 220
347
378
493
461
431
463
Geomatics Services, Ministry of Agriculture
Data Source: Survey data - Agriculture Knowledge Centre and Crops Branch IDW interpolation (power 2.5, fixed radius 300 km)Collaboration with:
© 2018 Government of Saskatchewan
Projection: UTM Zone 13 Datum: NAD83
0 50 100 150 20025
Kilometers
1:3,200,000
September 24, 2018
NOTE: Since techniques used to smooth the transition between zones can affect the values in localized areas,this map should be used for regional analysis only.
285290
161 159
67
5
Pea leaf weevil in Saskatchewan - 2018
Source: Government of Saskatchewan, Agriculture and Knowledge Centre and Crops Branch, 2018
Edmonton Lloydminster
Red Deer
Calgary
Lethbridge
Medicine Hat
>0 – 1 >1 – 3 >3 – 9>9 – 27>27
0
Average notches per plant
Average notches per plant
0 – 1 >1 – 3 >3 – 9>9 – 27>27
Pea Leaf Weevil Management Guide 10
What’s at stake?High pea leaf weevil populations can destroy up to 90 percent of the root nodules. Larval feeding on the nitrogen-fixing root nodules (Rhiozobium) of the plant can result in:
• Significant yield losses • Weaker plants that are less drought
tolerant and produce less seedAdult feeding on the leaves and growing point of seedlings can result in:
• Adult feeding on the leaves and growing point of seedlings can result in economic losses due to reduced yield. • Plants can typically withstand 50 percent
defoliation without the damage impacting yields. The difficult-to-see larval feeding on nodules is where the major losses occur.
Root nodule damage caused by the pea leaf weevil larvae
Leaf damage caused by the adult pea leaf weevil
Pea Leaf Weevil Management Guide 11
Management practices1. Plant early to maximize yields and
potentially avoid weevil damage in colder temperatures.
2. No-till cropping systems, integrated pest management systems and good crop rotations are recommended.
3. Registered seed treatments are recommended as your first line of defense. Not only do seed treatments protect against adults feeding on the foliage but they also delay and reduce egg-laying, preventing larvae feeding on Rhizobium nodules.
4. Trap crops can be planted along field borders in the fall or early spring. If warranted, spray trap crops with a registered insecticide to control pea leaf weevils before they move into the main crop.
5. Scout for pea leaf weevils as soon as peas and faba beans emerge and continue up to the six-node growth stage.
Pea Leaf Weevil Management Guide 12
Management practices6. Foliar applications of insecticide are
recommended at the two- to three-node stage when one or more feeding notches appear in three out of 10 seedlings. If feeding damage occurs only on the lower leaves and not on the clam leaf, the weevil is no longer a threat to the crop.
Source: Alberta Agriculture and Forestry
Pea Leaf Weevil Management Guide 13
Scouting • Begin scouting as soon as the plants emerge, and continue up to the six-leaf stage. Eggs laid after this period don’t affect yield.
• Pea leaf weevil is not an easy insect to spot as it ‘plays dead’ and drops to the ground on approach. Evidence of its presence comes from crescent-shaped notches on pea leaves.
• Economic threshold for foliar application: When one or more crescent-shaped notches appear on the clam leaf (most recently emerged leaves) in 30 percent of pea seedlings (three out of every 10 plants along a seeded row).
There is no economic threshold established for faba beans
Pea Leaf Weevil Management Guide 14
ScoutingAssessing pressure in peasLook at 10 adjacent seedlings in 10 areas of the field. Count what proportion of the seedlings have damage on the clam leaf. Calculate the average damage for all 10 areas. Make sure to select five areas on the edge of the field and five areas at least 30 metres into the field.
Pea Leaf Weevil Management Guide 15
Watch your pulse crops grow faster and stronger
Cruiser Maxx® Vibrance® Pulses seed treatment combines an effective insecticide with three fungicides to protect your pulse crops. Plus, Cruiser Maxx Vibrance Pulses delivers Rhizoctonia control as well as:
• The broad-spectrum seed- and soil-borne disease protection of Vibrance Maxx plus the early-season insect protection of Cruiser® 5FS insecticide
• Improved yield potential due to better plant stands, root systems, uniformity and overall plant health
• Contact and systemic activity that protects growing seedlings from both insects and diseases
• Compatibility with Rhizobium-based inoculants and seed safety
(Check inoculant suppliers of Rhizobium for details on compatibility)
Pea Leaf Weevil Management Guide 16
How does it work? • Moves systemically through the plant as it grows • When the adult pea leaf weevil feeds on the new leaves, it ingests the active ingredient, thiamethoxam
• The insect will stop feeding and delay egg laying. This greatly reduces the number of larvae feeding on nodules
Application tips • May be applied on-farm or by commercial treaters using closed transfer (including closed mixing, loading, calibrating, and closed treatment equipment)
Pea Leaf Weevil Management Guide 17
Use ratesCruiser Maxx Vibrance Pulses can be applied on-farm, provided a closed-system treater* is used, or by commercial seed treaters:• Cruiser 5FS @ 50 mL/100 kg of seed• Vibrance Maxx @ 335 mL/100 kg of seed (Apron Maxx® RTA @ 325 mL/100 kg of seed and Vibrance 500FS @ 10 mL/100 kg of seed)or• Cruiser 5FS @ 50 mL/100 kg of seed• Vibrance Maxx RFC @ 100 mL/100 kg of seed• Add water to create slurry volume of 325 mL/100 kg of seed
* Cruiser Maxx Vibrance Pulses must be applied using a closed-system seed treater. Please contact your local Syngenta Representative for further information.
Pea Leaf Weevil Management Guide 18
Why use a seed treatment? • Insect pests can severely limit growing
success. The best way to protect nodulation in fields infested with pea leaf weevil is with a seed treatment
• Alberta Agriculture reports research has shown seed treatment is much more effective in decreasing losses from pea leaf weevil than foliar treatment.
Refer to product label for a complete list of pests, application timing, rates and directions for use.
Pea Leaf Weevil Management Guide 19
Matador® foliar insecticide will protect your crop by controlling pea leaf weevil on contact
• Works on contact and through ingestion for up to seven days
• Fast-acting activity on adult pea leaf weevils • Registered for ground and aerial application in field peas and faba beans
Application timing • Make first application after plant emergence but prior to the five- to six-node stage
• Apply while adults are still present on the plants, before egg laying begins
Application tips • Recommended rate for pea leaf weevil is 34 mL/ac
• For best results, apply Matador in the early morning, before temperatures rise, and in the evening, after the heat of day
• Temperature must be warm enough for insects to be active at the time of application
Pea Leaf Weevil Management Guide 20
Packaging • One jug treats 111 acres when applied at 34 mL/ac
Water volume • Ground: 40-80 L/ac (10-20 gal/ac) • Air: 4-16 L/ac (1-5 gal/ac)
Pre-harvest interval • Do not apply within 21 days of harvest for dry peas
Refer to product label for a complete list of pests, application timing, rates and directions for use.
Pea Leaf Weevil Management Guide 21
Voliam Xpress® foliar insecticide will provide both rapid knockdown and long- lasting residual control of pea leaf weevil
• Works on contact and through ingestion • Initial and residual control is contingent upon thorough crop coverage
Application timing In pulses:
• Apply no later than when the first feeding is seen on foliage. Reapply after seven days depending on the presence of significant populations as determined by local monitoring
Packaging • Case: 4 x 3.78 L (treats 40 ac/jug or 160 ac/
case at the standard rate for most registered pests)
Water volume • Ground: minimum 10–20 gal/ac (100–200 L/ha)• Aerial: 4 gal/ac (40 L/ha)
For more information, visit Syngenta.ca or contact our Customer Interaction Centre at 1-87-SYNGENTA (1-877-964-3682).
Always read and follow label directions. Cruiser Maxx Vibrance Pulses is an on-seed application of (i) Cruiser 5FS Seed Treatment insecticide; (ii) Apron Maxx® RTA Seed Treatment fungicide or Apron Maxx RFC Seed Treatment fungicide and (iii) Vibrance 500FS Seed Treatment fungicide. Apron Maxx®, Cruiser®, Cruiser Maxx®, Matador®, RTA®, Vibrance®, Voliam Xpress® and the Syngenta logo are trademarks of a Syngenta Group Company. © 2018 Syngenta.
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