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Weed and Disease Problems
in Soybean
Tomislav Duvnjak
Agricultural Institute Osijek
CROATIA
Danube Soya Innovation and Research: Current status and future plans, 7th May 2015, Berlin
WEEDS
Outstanding competitors to cultivated plants in terms of
space, water, nutrient as well as light
Presented everywhere and more resistant than cultivated
plants (high or low temperatures, drought, long and heavy
moisture/rain, etc.)
Cause losses by reducing yields through interference
(competition) by lowering crop quality and by hindering
harvest.
Weeds can be most effectively managed in soybeans with a
well-planned program:
• a thorough analysis of the field situation,
• use of a combination of cultural practices,
• use of appropriate herbicides.
The most effective weed control system depends of:
• kinds of weeds in the field
• soil characteristics,
• tillage practices,
• crop rotation,
• and soybean row width.
Broadleaf weeds
Ambrosia artemisiifolia
Amaranthus retroflexus
Amaranthus hybridus
Abutilon theophrasti
Capsella bursa-pastoris
Chenopodium polyspermum
Chenopodium album
Datura stramonium
Fallopia convolvulus
Galinsoga parviflora
Hibiscus trionum
Matricaria chamomilla
Polygonum lapatifolium
Polygonum persicaria
Sinapis arvensis
Solanum nigrum
Sonchus asper
Sochus oleraceus
Stellaria media
Veronica agrestis
Veronica persica
Xanthium strumarium
Grass weeds
Echinocloa crus-galli
Setaria glauca
Setaria viridis
Digitaria sanguinalis
Panicum
dichotomiflorum
Panicum capillare
Broadleaf weeds
Cirsium arvense
Cichorium intybus
Convolvulus arvensis
Symphytum officinale
Daucus catora
Lathyrus tuberosus
Rumex obtusifolius
Sonchus arvensis
Calystegia sepium
Grass weeds
Sorghum halepense
Agropyron repens
Cynodon dactylon
Poa pratensis
ANNUAL PERENNIAL
Chemical weed treatment
pre-sowing
pre-emergence
post-emergence
broadcast applied
band applied
Agricultural management
Crop rotation
Inter-row cultivation
The bottom line of any weed management decision is cost.
Aplying band rather than broadcast herbicide and cultivate
once, annual savings on 100 ha could be 1100 – 2650 Euro.
Helps avoid development of herbicide-resistant weeds.
Inexpensive way to control weeds that escape broadcast
treatment.
Commonly used in row crop production (combined with a band of herbicide
applied over the crop row).
Inter-row cultivation can be a means to reduce herbicide use.
Benefit – the most attributed to weed control, also improved soil aeration and
reduced soil compaction, may increase available water.
Soybean injury can occur with certain herbicides,
particularly when stressed from adverse environmental
conditions.
Certain additives can enhance injury from postemergence
herbicides.
Herbicides persistence in soil and potential injury to
rotational crops.
Important role in in disease epidemiology in all branches of
plant production.
Weeds enables pathogen survival in extreme environmental
conditions and in absence of the main host for several years.
As alternative hosts, connect vegetation years, host and
locations – epidemiological or green bridges.
“Parasite mycopopulation of weeds in row crops”
“Role of weeds in epidemiology of diseases of row crops”
Abutilon theophrasti: Wild host for three fungal parasites of soybean
First Report of Phomopsis longicolla on Cocklebur ( Xanthium
strumarium ) in Croatia
Xanthium strumarium L. as the host to the fungi Sclerotinia
sclerotiorum (Lib.) de Bary
DESEASES
Fungal
Bacterial
Viral
Nemathodes
More than 100 pathogens are known that affect soybean,
about 35 are importan economically.
All plant parts are susceptible to a number of pathogens:
seed rots and seedling diseases, foliar diseases, root and stem
diseases.
Reduces quality and quantity of grain yield.
Often reduces soybean yield.
As number of hectares under soybean increase, increase the
number and severity of soybean diseases.
The economic importance of any single disease may vary
from one geographic area to another in any one season.
Conservative estimation of worldwide losses to all soybean
diseases is about 11% of the amount produced.
Bacterial diseases
Bacterial blight Pseudomonas amygdali pv. glycinea
Bacterial pustules Xanthomonas axonopodis pv. glycines
= Xanthomonas campestris pv. glycines
Bacterial tan spot Curtobacterium flaccumfaciens pv. flaccumfaciens
= Corynebacterium flaccumfaciens pv. flaccumfaciens
Bacterial wilt Curtobacterium flaccumfaciens pv. flaccumfaciens
Ralstonia solanacearum = Pseudomonas solanacearum
Wildfire Pseudomonas syringae pv. tabaci
Viral diseases
Alfalfa mosaic genus Alfamovirus, Alfalfa mosaic virus (AMV)
Bean pod mottle genus Comovirus, Bean pod mottle virus (BPMV)
Bean yellow mosaic genus Potyvirus, Bean yellow mosaic virus (BYMV)
Brazilian bud blight genus Ilarvirus, Tobacco streak virus (TSV)
Cowpea chlorotic mottle genus Bromovirus, Cowpea chlorotic mottle virus (CCMV)
Mung bean yellow mosaic genus Begomovirus, Mung bean yellow mosaic virus (MYMV)
Peanut mottle genus Potyvirus, Peanut mottle virus (PeMoV)
Peanut stripe genus Potyvirus, Peanut stripe virus (PStV)
Peanut stunt genus Cucumovirus, Peanut stunt virus (PSV)
Soybean chlorotic mottle genus Caulimovirus, Soybean chlorotic mottle virus (SbCMV)
Soybean crinkle leaf genus Begomovirus, Soybean crinkle leaf virus (SCLV)
Soybean dwarf genus Luteovirus, Soybean dwarf virus (SbDV)
Soybean mosaic genus Potyvirus, Soybean mosaic virus (SMV)
Soybean severe stunt genus Nepovirus, Soybean severe stunt virus (SSSV)
Tobacco ringspot = bud
blight genus Nepovirus, Tobacco ringspot virus (TRSV)
Phomopsis longicolla (PL)
Phomopsis seed decay
Diaporthe phaseolorum var. caulivora (DPC)
Stem canker
Diaporthe phaseolorum var. sojae (DPS)
Pod and stem blight
DIAPORTHE/PHOMOPSIS Complex (D/P)
on soybean in Europe
Different field damage