Herbicides

Question 1

Name 3 factors that govern the Selectivity of Selective Herbicides?

Answer 1

1) Application Rate - i.e only works at certain rate
2) Timing - ie applied when crop is safe
a) Before Emergence
b) Crop has undergone morphological Changes eg Leaf Waxing in peas
3) Sowing depth
4) Physiology - Different Absorption, Movement, Biological activities

Question 2

State 2 Selective Herbicides?

Answer 2

1) Graminicides - Grass Weeds
2) Hormone Inhibitors - Broadleaved Weeds

Question 3

State 4 Occasions when a Non-Selective Herbicide is appropriate?

Answer 3

1) Weed control in stubbles
2) Green Bridge Destruction
3) Applied to Stale Seed beds
4) Cover Crop Desiccation
5) Weed control on Overwintered Ploughing

Question 4

How to Residual Herbicides work?

Answer 4

Taken in by roots and/or shoot and transported to site via the Xylem

Question 5

What factors are required for optimum Efficacy of R. Herbicides?

Answer 5

1 - Adequate Moisture - Rolled beds, Irrigation, Rain
2 - Fine seedbeds - No Clods

Question 6

State two cases based on soil structure when application rates of R. Herbicides would be altered?

Answer 6

1 - High OM or Clay = Higher rates (Risk of Lockup)
2 - Sandy Soil = Lower Rates (Leaching and Crop damage risk)

Question 7

How do Foliar Herbicides Work?

Answer 7

Transported through leaf cuticle by diffusion

Question 8

For F. Herbicides, state the 2 activities once inside the leaf?

Answer 8

1 - Contact ie scorch (Leaf coverage is essential, Minimal movement of Herb)
2 -Translocated ie moves downward.

Question 9

At what growing point is it best to apply a F.Herb that works by translocation?

Answer 9

1 - When plant is actively growing

Question 10

Name 4 herbicide chemical Groups and their M.O.A?

Answer 10

1 - Fops - ACC Inhibitors ie prevents leaf wax production (Foliar)
2 - Dims - ACC Inhibitors ie prevents leaf wax production (Foliar)
3 - Sulfonylureas - ALS Inhibitors (Foliar & Residual)
4 - Uracils - Photosystem II Inhibitors (Foliar)
5 - Pyridine-carboxylates - Auxin Mimic ie Hormone (Foliar)

Question 11

Name 4 Herbicides and Active Ingredients?

Answer 11

1 - Fusilade Max (fluazifop-P-butyl) - Fops
2 - Centurion Max (clethodim) - Dims
3 - Titus (rimsulfuron) - Sulfonylureas
4 - Venzar (lenacil) - Uracil
5 - Shield Pro (clopyralid) - Pyridine-Carboxylates

Question 12

Name a foliar Herbicide approved for Broad-leaved Crops?

Answer 12

1 - Laser (cycloxydim)
2 - Centurion Max (clethodim)
3 - Shogun (propaquizafop)

Question 13

Name 4 Residual Acting Herbicides?

Answer 13

1 - Wing P (dimethenamid-P + PMP)
2 - Gamit (chlomazone)
3 - Stomp (pendimethalin)
4 - Sultan (metazachlor)
5 - Dual Gold (s-metalachlor)
6 - Kerb (propyzamide)

Question 14

Name 4 Foliar Acting Herbicides?

Answer 14

1 - Shield Pro (clopyralid)
2 - Laser (cycloxydim)
3 - Centurion Max (clethodim)
4 - Falcon (propaquizafop)
5 - Fusilade (fluazifop-P-butyl)

Question 15

Name a total Herbicide with translocated activity

Answer 15

Gylphosate (Roundup)