Weed Control and Issues in Developing Countries

1
Weed Control and Issues in Developing Countries

• Peter R Hobbs
• 609 Bradfield
• Department Crops and Soil Science

2
Challenge for Agriculture

• To increase food production sustainably to meet
  food security needs of a growing population now
  and in the future while at the same time
  minimizing the effects on the environment and
  improving the livelihoods of those involved in
  agriculture
• Improve the efficiency of natural resource use
  needed for agriculture

3
Convergence of opinions

• Demand for food - increasing
• Harvested area - possibly shrinking
• Traditional sources of productivity growth are
  they exhausted?
• More competition for blue water
• More severe weather as a result of GHG emissions
  and global climate change
• In addition, there is resource and environmental
  degradation?

4
Resource Poor Farmers?Subsistence Farmers?

• Not produce enough food to feed their family or
  market any excess. Nutritional quality of food
  produced can also be poor.
• Lack basic infra-structure to transport, store
  and sell the food they grow
• Lack income and access to credit to invest in new
  technology
• Little capacity to manage risks associated with
  technology

5
South Asia
Pakistan
IGP
Nepal
Bangladesh
India
6
Indo-Gangetic Plains

• The population of South Asia is over 1.5 billion
  and increased at 1.8 per year over last 6 years.
  27.3 million more mouths to feed each year!!
  75K/day 3,116/hr
• (IRAQ 23 million NY Mass 25m
• More than 400 million are poor (lt 1/day)
• The per capita rice-wheat growing areas have
  shrunk from 1200 m2 in 1961 to less than 700 m2
  in 2000.
• Demand for rice and wheat will grow at 2.5 per
  year in the next 20 years. This has to come from
  yield growth.

7
Source Indian Census Report
8
Population Dynamics
9
Population density in RW area of Indo-Gangetic
Plains
RW area population 280 million RW area pop
density 517 /sq km Green area population 430
million Green area pop density 452 /sq km
Mid-hills North Transition South
Source Dave Hodson, GIS Lab, CIMMYT
RW zone
10
Rice-wheat systems in South Asia

• Rice and wheat grown in the same calendar year in
  S. Asia (13.5 m has)
• Rice in the wet monsoon summer and wheat in the
  dry cool winter
• Rice grown by puddling soil and transplanting
  seedlings
• This creates a problem for the next wheat crop
  because of poor soil physical properties
• This also affects soil biology

11
R-W Systems Calendar
Month
Summer
Winter
J
F
M
A
M
J
J
A
S
O
N
D
J
F
M
A
Rice
Wheat
Wheat
Wheat
Rice-1
Rice-2
Wheat
Rice
NR
Wheat
Wheat
Wheat
GM
Rice
Wheat
There are also rotations of RW with Sugarcane
NR potato, vegetable, legume, oilseed
12
Phalaris minor issue

• This WAS a major problem in NW India and Pakistan
  in wheat in the 1990s.
• Herbicide resistant Phalaris to Isoproturon
  started show in early 1990s
• It became a major problem by mid-1990s
• Need for integrated weed management approaches
• rotations, tillage, seed, variety etc.

13
Promote Integrated Weed Management Systems

• Hand weeding
• Rotations use of a fodder crop
• Inter-cultivation
• Mulching allelopathic properties of some
  residues and cover crops
• Prevent seed set of weeds
• Clean seed
• Use herbicides when needed in proper manner
• Etc.

14
Crisis in Haryana (and Punjab, UP)

• Herbicide tolerant Phalaris minor seen as early
  as 1992-93 wheat season
• Crisis level reached by 1995-96
• In affected fields, Phalaris populations up to
  3000 plants/ m3 wheat crop squeezed out
• Problem spreading fast into neighboring states

Photo LW Harrington
15
Phalaris minor (little seeded canarygrass)
16
A desperate search for solutions

• Improved management - crop rotations, timely
  sowing, clean seed, etc. of limited help
• New herbicides
• Zero tillage (?)
• Major role played by R.K. Malik, Haryana
  Agricultural University

Photo LW Harrington
17
Grain yield of wheat and population of Phalaris
under zero and conventional tillage.
Source RK Malik and scientists at Haryana
Agricultural University
18
Another pleasant surprise

• It took the Phalaris crisis for farmers to try
  no-till
• Result of farmer trials huge enthusiasm for
  cost reduction
• Increasing number of projects, farmer trials
• Traveling seminars helped promote awareness
  in1998
• Private sector kept improving implements

Photo LW Harrington
19
Means and ends keep changing!

• No till originally seen as a means of advancing
  sowing dates
• Breakthrough with farmers came with no-till as a
  means of helping control Phalaris minor
• Essential local manufacturers were involved and
  linked to farmers
• Continued farmer interest in no-till as a means
  of reducing costs

Photo LW Harrington
20
New Herbicides

• Topik -- Clodinafop
• Puma -- Fenoxyprop
• Leader Sulfosulfuron -- Sulfonylurea
• Grasp -- Tralkoxydim
• Need to be applied with a sprayer low
  quantities active ingredient used per hectare
  used (10-50 grams/ha)

21
No-Tillage with Inverted-T

• Based on inverted-T coulter from NZ
• Good where no loose residues including anchored
  straw
• Locally made and low cost
• Can adapt present farmer machinery
• Uses 15-25 less water
• Less weeds germinate
• Service providers means small farmers can use

22
No-Till
Conventional
23
Phalaris population over time
24
Herbicide Application Using Knapsack Sprayers
essential
A. Miller and R. Bellinder, Cornell University,
in cooperation
with Dr. R.K. Malik (HAU), Dr. L.S. Brar (PAU) G.
Singh (GBPUAT Pantnagar) J. Ranjit (NARC)
and Dr. P. Hobbs (CIMMYT)
25
Resource poor farmer systems for herbicide
application
26
Los Banos, Philippines. Puddling rice soils with
carabao
27
Rice planting methods
28
Weeding in Rice
29
Taiwan Girls weeding rice
30
No-till rice-wheat

• In order to get the full benefit of no-till
  wheat, also need to no-till rice
• Problems of weeds because difficult to pond water
  when no puddling
• Traditionally hand weeded
• Tedious and usually done by women
• One solution would be to introduce herbicide
  resistant rice varieties
• Use of cover crops

31
Other Future Issues Rice

• Better 0-till and DSR varieties
• Oryza sativa by O. glaberimma crosses
• Chromosome substitution lines
• Use of Genetic Engineering
• Roundup ready rice
• Blast resistant rice
• Drought tolerant rice
• Improved equipment for seeding rice

32
Herbicide Tolerant (HT) Rice
Weed Control Mechanical, Herbicides
Herbicides Broad Spectrum ie. Glyphosate,
Glufosinate Narrow Spectrum ie. 2,4 - D LD50
4320 mg/kg DDT 115 Parathion 30 Bt gt5000
33
Herbicide Tolerant (HT) Crops

• Gene Source various bacteria
• How does it work
• Insert gene for herbicide de-toxification
• Replace herbicide target with gene that is
  resistant to herbicide

34
Benefit of HT to Environment?

• Depends on Herbicide not GM Plant
• Post emergence broad spectrum Roundup herbicide
  replace numerous narrow spectrum herbicides that
  are more toxic
• Depends on breakdown product of herbicide in
  plant/soil
• Allows farmer to practice no-till and
  conservation agriculture practices

35
Negative issues

• Weeds used for fodder
• Employment of the poor for weeding
• Availability of technology to resource poor
  farmers
• Credit to buy sprayer and herbicide
• Training in proper use
• Spurious products on the market
• Extension of improved system poor

36
Maize in Zambia -- Traditional
37
Zambia Basin System
38
Conservation Agriculture Residue retention
distinguishes Conservation Agriculture from
conventional farming systems, which are
characterized by leaving the soil bare and
unprotected, exposed to climatic agents.
The soil cover is not incorporated into the soil
by tillage.
(FAO, 2002)