A survey of problem weeds of sorghum and their management in two sorghum-producing districts of Zimbabwe

Figures & data

Table 1. Weeds reported to be associated with sorghum

Weed species	Common name	Family	Reference
Abutilon theophrasti Medik	Velvetleaf	Malvaceae	Ziska (2003)
Acanthospermum hispidum DC.	Upright starbur	Asteraceae	Centre for Agriculture and Bioscience International (CABI) (2019)
Amaranthus hybridus L.	Slim amaranth	Amaranthaceae	Tadesse, (2008)
Amaranthus retroflexus L.	Redroot amaranth	Amaranthaceae	Ziska (2003)
Ageratum conyzoides L.	Tropical whiteweed	Asteraceae	Filho et al. (2014), Tadesse (2008)
Argemone Mexicana L.	Mexican pricklypoppy	Papaveraceae	Tadesse (2008)
Bidens pilosa L.	Hairy beggarticks	Asteraceae	Filho et al. (2014), Tadesse (2008),
Chenopodium album L.	Lambsquarters	Chenopodiaceae	CABI (2019)
Commelina benghalensis L.	Benghal dayflower	Commelinaceae	Filho et al. (2014), Tadesse (2008)
Convolvulus arvensis L.	Field bindweed	Convolvulaceae	Tadesse (2008)
Conyza bonariensis (L.) Cronquist	Asthma weed	Asteraceae	Filho et al. (2014)
Cynodon dactylon (L.) Pers.	Bermudagrass	Poaceae	Tadesse (2008)
Cynodon nlemfuensis Vanderyst	African bermudagrass	Poaceae	Tadesse (2008)
Cyperus esculentus L.	Yellow nutsedge	Cyperaceae	Tadesse (2008)
Cyperus rotundus L.	Purple nutsedge	Cyperaceae	Tadesse (2008)
Datura stramonium L.	Thorn apple	Solanaceae	Tadesse (2008)
Digitaria sanguinalis (L.) Scop.	Hairy crabgrass	Poaceae	Filho et al. (2014)
Echinochloa crus-galli (L.) P. Beauv.	Barnyardgrass	Poaceae	Tadesse (2008)
Eleusine indica (L.) Gaertn.	Goosegrass	Poaceae	Filho et al. (2014), Tadesse (2008)
Euphorbia hirta L.	Asthma plant	Euphorbiaceae	Tadesse (2008)
Euphorbia heterophylla L.	Mexican fireplant	Euphorbiaceae	Filho et al. (2014)
Galinsoga parviflora Cav.	Gallant soldier	Asteraceae	Filho et al. (2014), Tadesse (2008)
Gynandropsis gynandra L.	Spiderwisp	Capparaceae	Tadesse (2008)
Ipomoea spp.	Morning-glory	Convolvulaceae	CABI (2019)
Nicandra physalodes (L.) Scop.	Apple of Peru	Solanaceae	Tadesse (2008)
Oxalis spp	Pink garden sorrel	Oxalidaceae	Tadesse (2008)
Panicum spp.	Panicgrass	Poaceae	Tadesse (2008)
Portulaca oleracea L.	Little hogweed	Portulacaceae	Filho et al. (2014), Tadesse (2008)
Richardia brasiliensis Gomes	Mexican clover	Rubiaceae	Filho et al. (2014)
Rottboellia cochinchinensis (Lour.) W.D. Clayton	Itchgrass/Shamvagrass	Poaceae	Valverde (2003), Tadesse (2008)
Setaria spp.	Foxtail	Poaceae	Tadesse (2008)
Striga asiatica (L.) Kuntze	Asiatic witchweed	Scrophulariaceae	Mrema et al. (2016), Tadesse (2008)
Striga hermonthica (Delile) Benth.	Purple witchweed	Scrophulariaceae	Mrema et al. (2016), Tadesse (2008)
Tagetes minuta L.	Mexican marigold	Asteraceae	Tadesse (2008)
Xanthium strumarium L.	Giant cocklebur	Asteraceae	Tadesse (2008)

Table 2. Reported herbicide resistance in weeds associated with sorghum

Weed species	Site of action
Echinochloa crus-galli	EPSP synthase inhibitors, ALS inhibitors, Synthetic auxins, ACCase inhibitors, Cellulose inhibitors, Microtubule inhibitors, Photosystem II inhibitors, long chain fatty acid inhibitors, Lipid inhibitors
Abutilon theophrasti	Photosystem II inhibitors
Galinsoga parviflora	ALS inhibitors
Amaranthus hybridus	EPSP synthase inhibitors, Synthetic auxins
Bidens pilosa	ALS inhibitors, Photosystem II inhibitors, PSI electron diverter, EPSP synthase inhibitors
Cyperus esculentus	ALS inhibitors
Chenopodium album	Photosystem II inhibitors, ALS inhibitors
Convolvulus arvensis	PSI electron diverter
Datura stramonium	Photosystem II inhibitors
Digitaria sanguinalis	ACCase inhibitors
Eleusine indica	EPSP synthase inhibitors, PSI Electron Diverter, ACCase inhibitors, Glutamine synthase inhibitors, Microtubule Inhibitors, Photosystem II inhibitors, PPO inhibitors
Euphorbia heterophylla	ALS inhibitors
Rottboellia cochinchinensis	ACCase inhibitors, ALS inhibitors
Xanthium strumarium	Nucleic acid inhibitors, ALS inhibitors,

Source: Adapted from Heap 2019.

Figure 1. Temperature and rainfall data for Chipinge (a) and Insiza (b) districts in the 2016/17 season

Table 3. Summary of sampling strategy used

District	No. of wards	Main sorghum growing wards	Randomly sampled wards	No. of households in sorghum growing wards	No. of growers in wards	Dominant producers in wards	Target sample/district
Chipinge	30	6	3	55000	3600	1100	45
Insiza	23	5	3	30400	7000	2134	45
Total	53	11	6	85400	10600	3234	90

Table 4. Weed management methods used in Insiza and Chipinge districts (N = 80)

Weed management method	% of respondents
Hand weeding	85
Mechanical control	13
Herbicide application	2

Table 5. Hand hoeing frequency

Weeding frequency	% of respondents
Once	14
Twice	42
Thrice	44

Table 6. Major weeds recorded (per square metre) in sorghum fields in Chipinge and Insiza districts

Chipinge		Insiza
Weed species	No. of weeds/m^2	Weed species	No. of weeds/m^2
Acanthospermum hispidum	2	Acanthospermum hispidum	3
Tagetes minuta	12	-	-
Eleusine indica	8	Eleusine indica	6
Bidens pilosa	3	Bidens pilosa	6
Commelina benghalensis	9	-	-
Cynodon dactylon	5	Cynodon dactylon	2
Amaranthus hybridus	21	-	-
Striga asiatica	10	Striga asiatica	4
Cleome monophylla	6	-	-
Richardia scabra	14	-
Cyperus esculentus	5	-	-
Cyperus rotundus	3	-	-
Cochorus spp	2	-	-
Datura stramonium	8	-	-
Setaria verticillata	4	-	-
Tribulus terrestris	5	-	-
-	-	Panicum spp.	8

Table 7. Comparison of weeds reported in current survey and those reported in 1988

1988 weed survey	Current survey	1988 weed survey	Current survey
Matabeleland North & South Provinces	Insiza district	Manicaland Province	Chipinge district
Acanthospermum hispidum	p	Acanthospermum hispidum	p
Amaranthus hybridus	a	Eleusine indica	p
Bidens pilosa	p	Bidens pilosa	p
Commelina benghalensis	a	Commelina benghalensis	p
Cyperus esculentus	a	Cynodon dactylon	p
Tagetes minuta	a	Amaranthus hybridus	p
Eleusine indica	p	Striga asiatica	p
Portulaca oleracea	a	Striga spp	a
Striga asiatica	p	Tagetes minuta	a
Striga spp.	a	Eragrostis aspera	a
Nicandra physalodes	a	Nicandra physalodes	a
Rottboellia cochinchinensis	a	Cleome monophylla	p
Cyperus rotundus	a	Richardia scabra	p
Galinsoga parviflora	a	Ceratotheca sesamoides	a
Ocimum canum	a	Cyperus esculentus	p
Jacquemontia tamnifolia	a	Cyperus rotundus	p
a	Cynodon dactylon	Hibiscus meeusei	a
a	Panicum spp	Vernonia cinerea	a
		Vernonia poskeana	a
		Urochloa panicoides	a
		Ocimum canum	a
		Euphorbia heterophylla	a
		Gisekia Africana	a
		Crotolaria laburnifolia	a
		a	Cochorus spp
		a	Datura stramonium
		a	Setaria verticillata
		a	Tribulus terrestris

Key: a = absent; p = present

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