Control cost ($) per hectare

Crop market value ($) per hectare

250

300

350

400

450

500

550

600

650

700

750

Percentage of seedlings infested at the one true-leaf stage

15

15

12

11

10

9

8

7

6

6

5

5

20

20

16

14

12

11

10

9

8

8

7

7

25

25

20

17

15

13

12

11

10

10

9

9

30

30

25

21

18

16

14

13

12

11

11

10

Percentage of seedlings infested at the two true-leaf stage

15

26

21

18

16

14

13

12

11

11

10

10

20

35

28

23

20

18

17

16

15

14

13

13

25

44

35

29

25

23

21

19

18

17

16

16

30

52

43

36

31

28

25

23

21

20

19

18

Percentage of seedlings infested at the three true-leaf stage

15

67

53

46

41

36

33

31

29

27

25

24

20

89

72

61

54

49

44

40

37

35

33

32

25

*

90

76

67

61

55

50

46

43

40

38

30

*

*

91

81

73

66

60

55

51

47

44