Resistance to Glyphosate in Populations of <i>Digitaria insularis</i>

COSTA, N.V.; MORATELLI, G.; FERREIRA, S.D.; SALVALAGGIO, A.C.; RODRIGUES-COSTA, A.C.P.

doi:10.1590/S0100-83582018360100131

ABSTRACT:

The intensive use of glyphosate can select resistant populations. This study aimed at evaluating the occurrence of glyphosate resistance in populations of D. insularis in agricultural areas. Three experiments were conducted in randomized block experimental design with four replications. The Resistance Degree (RD) was determined by a dose-response curve in the evaluated populations: Experiment 2012, São Camilo (R01 and R02) and Palotina (R03, R04 and S05-susceptible); Experiment 2013 Palotina (R06 and R12), Katueté/Paraguay (R07), Toledo (R08 and R10), Cascavel (R09), São Miguel do Iguaçu (R11), Dom Eliseu/Pará (S13-susceptible); Experiment 2015 Nova Aurora (R14), Iracema do Oeste (R15 and R16), Jesuitas (R17 and R18), Tupãssi (R19), Jotaesse (R20), Espigão Azul (R21) and Palmitopolis (S22- susceptible). In 2012, it was possible to confirm a moderate resistance (RD = 1.1 to 5.0) only in R03; and populations R01, R02 and R04 were highly resistant (RD>5.0). In 2013, populations R09, R10, R11 and R12 showed resistance, while R06, R07 and R08 were highly resistant. In 2015, the R14, R16, R18, R19 and R20 populations showed moderateresistance, and R15 and R18 were highly resistant. Only R21 was susceptible. It was found that 83% of producers use the no-tillage system, 100% use the succession soybean/corn with 90% transgenic varieties, 45% of producers cannot explain the procedure regulation/sprayer calibration. Around 62% use practices to prevent the selection of resistant biotypes. Resistance was confirmed in 89.5% of the populations. The adopted agronomic practices may explain these results.

Keywords:
sourgrass; agricultural practices; weed; herbicide

[1] * Corresponding author: <neumarcio.costa@unioeste.br>

Year	Population	Location	Coordinates	Sowing system
2012	R01	São Camilo⁽¹⁾	24^o14’35.89” S / 53^o53’35.73” W	No-tillage
	R02	São Camilo⁽¹⁾	24^o12’01.78” S / 53^o56’43.84 W	Conventional
	R03	Palotina	24^o15’18.98” S / 53^o53’42.25W	No-tillage
	R04	Palotina	24^o16’18,64” S / 53^o53’15.58 W	No-tillage
	S05	Palotina	24^o14’03.54” S / 53^o52’03.04 W	No-tillage
2013	R06	Palotina	24˚14’03.54” S / 53˚52’03.04 W	No-tillage
	R07	Katuete - PY⁽²⁾	25˚40’21.31” S / 54˚44’11.60 W	No-tillage
	R08	Toledo	24^o71’48.97” S / 53˚68’63.28 W	No-tillage
	R09	Cascavel	24˚47’39.47” S / 53˚41’39.51 W	No-tillage
	R10	Toledo	24˚42’32.24” S / 53˚49’05.18 W	No-tillage
	R-11	São Miguel do Iguaçu	25˚25’21.24” S / 54˚13’02.99 W	No-tillage
	R12	Palotina	24^o17’37.0 S / 53^o49’41.9 W	Conventional
	S13	Dom Eliseu - PA⁽³⁾	04˚15’18” S / 47˚35’29 W	Conventional
2015	R14	Nova Aurora	24^o27’51.90” S / 53^o17’58.20 W	No-tillage
	R15	Iracema do Oeste	24^o27’17” S / 53^o20”19.10 W	No-tillage
	R16	Iracema do Oeste	24^o34’28.30 S / 53^o25’03.80 W	No-tillage
	R17	Jesuítas	24^o30’06.00 S / 53^o23’50” W	No-tillage
	R18	Jesuítas	24^o27’17” S / 53^o20’19,1 W	No-tillage
	R19	Tupãssi	24^o38’29.9 S / 53^o28’34.0 W	No-tillage
	R20	Jotaesse⁽⁴⁾	24^o34’39.5 S / 53^o30’24.4 W	Conventional
	R21	Espigão Azul⁽⁵⁾	24^o49’18.2 S / 53^o27’39.2 W	No-tillage
	S22	Palmitopolis⁽⁶⁾	24^o34’57.4S / 53^o22’36.5 W	No-tillage

Question	Option
1. Main cultivation system used in the property.	Conventional - No-tillage - Organic
2. Do you use crop rotation?	See producer response
3. What are the main herbicides used? 4. Do you use transgenic varieties?	See producer response Yes - No
5. Do you use the recommended dose of herbicides?	Yes - No
6. Do you understand the concept of resistance? 7. Do you use management practices to avoid resistance? 8. Do you adjust/calibrate the sprayer before the applications? 9. Can the producer explain how to perform the sprayer adjustment/calibration procedure?	Yes - No Yes - No Yes - No Yes - No

Year	Population	$y = \frac{a}{1 + e - (\frac{x - c_{50}}{b})}$
Year	Population	a	b	C₅₀	R²	P	RD
2012	R01	93.7468	513.7712	1193.1870	0.97	<0.0001	21.2
	R02	84.4114	438.9998	741.4787	0.83	0.0111	13.1
	R03	92.6560	151.1182	246.5553	0.93	0.0011	4.4
	R04	100.8447	19.1496	51.9011	0.99	<0.0001	1.0
	S05	99.9158	15.1750	56.4083	0.99	<0.0001	1.0
2013	R06	100.0537	208.3990	1436.3904	0.99	<0.0001	6.0
	R07	100.9667	473.7762	1889.2987	0.99	<0.0001	7.9
	R08	99.9221	514.1456	2438.0736	0.99	<0.0001	10.2
	R09	93.7708	172.6850	1201.4570	0.99	<0.0001	5.0
	R10	90.5208	310.0051	1096.9060	0.91	0.0024	4.6
	R11	91.0890	235.4546	1144.3032	0.95	0.0030	4.8
	R12	94.1316	170.5039	1207.2096	0.99	<0.0001	5.0
	S13	98.7030	58.8093	237.4046	0.99	<0.0001	1.0
2015	R14	100.4339	100.1183	231.1867	0.98	<0.0001	2.9
	R15	95.6211	760.4443	629.3600	0.82	0.0023	7.9
	R16	85.6515	218.0721	251.2081	0.90	0.0003	3.1
	R17	98.5216	951.3884	993.6637	0.81	0.0026	12.4
	R18	88.1046	234.2751	256.1433	0.86	0.0009	3.2
	R19	100.7695	55.5004	89.8850	0.94	<0.0001	1.1
	R21	100.1140	33.8552	81.0097	0.99	<0.0001	1.0
	R20	100.3045	51.5945	111.9962	0.99	<0.0001	1.4
	S22	99.9948	11.9522	80.1216	0.99	<0.0001	1.0

Brasil

Brasil

Resistance to Glyphosate in Populations of Digitaria insularis

Resistência ao Glyphosate em Populações de Digitaria insularis

ABSTRACT: