In fact, it is: b-r-:b-RR: BBR-:BBRR = 9: 3: 3:1,the result after removing BB, because BB is yellow, it died at seedling stage.

Expand b-r-:b-RR: BBR-:BBRR = 9: 3: 3:1,that is:

1BBRR-dark green disease resistance;

2 bbrr- dark green disease resistance;

2 bbrr- light green disease resistance;

4B BRR-light green and disease-resistant;

1BBrr-dark green is not resistant to disease;

2 bbrr- light green is not resistant to disease;

1bbRR-seedling death;

2 bbrr- seedling death;

1bbrr-seedling death.

See for yourself whether the result is as the title says.