Download AGR 3102

AGR 3102
PRINCIPLES OF WEED SCIENCE
Weeds in Orchards and Plantation Crops
Objective: To study the distribution and growth of weed species growing in orchards
and plantations
Materials
Digital camera
Note book (for recording)
Proper outfit for outdoor activities (boots/sneakers, cap/hat, etc.)
Introduction
Plantation crops (oil palm, rubber, coconut, cocoa, coffee etc.) and orchard (fruit
trees) often compose of perennial and big, tall trees. Plantations and orchards are
commonly infested by various weed species throughout the year and present major
problems of access and competition. Weeds compete with orchard and plantation
crops for light, soil moisture and nutrients and also serve as alternate hosts for insects
and pathogens. Therefore, management of weeds is an important cultural operation to
be followed in the plantations and orchards. However, in these areas vigorous weed
competition are mostly found during the early stages of crops growth, when trees are
still young and the canopy has not fully covered the ground. It is at this stage that the
weeds can cause a lot of problems, affecting management works etc. Maintenance of
groundcovers in the early phase of planting can minimize the weed infestation to a
great extent. However, during the first year till the cover crops are fully established,
the weeds that are sprouting around the cover crops patches should be controlled for
their early establishment. Once the ground cover is established, the weed management
operations need be concentrated only on the planting strips. Mulching and circle
weeding are also effective in controlling weeds in young orchards and plantations.
Weed management in small tree plantation and orchard such as tea, pineapple,
watermelon, and dragonfruit, however, is very critical, particularly during the early
establishment and post-pruning operation. Since those plants are not as big and tall as
other aforementioned plantation/orchard crops, weeds will grow and compete
profusely/freely at the time of planting and only become less competence when the
crops canopy covers the inter-row spaces adequately. These weeds need to be
controlled early to prevent from affecting or competing with the crops.
Practical Works
Identify and record the weeds from two different localities: plantation and orchard.
Take note on the growth of those weeds, associated with the type of crops. The
activity is to be done in groups, and submit the report individually.
Questions to Answer
1. What type of weeds grow close to the crop, and what types of weed grow at a
distance (in between crop rows)?
2. Are there differences in the weed species found in the plantation compared to the
ones found in orchard?
3. Which type of grasses, sedges, and broadleaves are more dominant and abundant,
and which are less in both localities?
AGR 3102
PRINCIPLES OF WEED SCIENCE
Weeds in Field Crops
Objective: To study the distribution and growth of weed species in the natural habitat
of field crop areas
Materials
Digital camera
Note book (for recording)
Proper outfit for outdoor activities (boots/sneakers, cap/hat, etc.)
Introduction
Field crops include maize, peanut, sweet potato, yam, vegetables, and rice. Field crops
are among major food crops in Malaysia, providing people of food source for daily
consumption. They are grown under several cropping system, thus creating many
different situations or habitats for weed growth. This therefore, allows many types of
weed species to grow under field crop situations. Weeds in the field and farm are
mainly grasses, sedges, and herbaceous broadleaves. These weeds interfere with crops
growth and yield through competition on light, water, nutrient, space and canopy, etc.
As a result, crop growth will be affected such as being stunted, further adversely
effect yield quantity and quality.
Practical Works
Identify and record the weed species and their nature of growth and composition
under different types of cropping system, type of crops, habitat, and crop density.
Questions to Answer
1. What are the types of weed species found for each crop/cropping system?
2. Is the weed composition the same when comparing with the previous crops you
have visited?
3. What are the common/dominating weed species and weed types for each field
crop?
AGR 3102
PRINCIPLES OF WEED SCIENCE
Landscape and Water Weeds
Objective: To study the distribution and growth of weed species growing in landscape
and aquatic habitat
Materials
Digital camera
Note book (for recording)
Proper outfit for outdoor activities (boots/sneakers, cap/hat, etc.)
Introduction
Weeds in landscape areas compete for growth and affect the aesthetic value of beauty
and scenery. In recreational areas such as sports field, parks and gardens, weeds can
also cause discomfort and interfere with recreational activities. Weed management in
landscape is often made difficult by the complexity of many plantings: usually more
than one species is planted in the landscaped area and there is a mix of annual and
perennial ornamentals. There are also considerations regarding public concern about
the use of chemicals to control weeds and their effect on water quality if the herbicide
moves offsite through runoff. The choice of a specific weed management program
depends on the weeds present and the types of turf or ornamentals planted in the area.
Because of the many variables, weeds in landscape plantings are usually controlled by
a combination of nonchemical and chemical methods.
Aquatic plants growing in ponds and lakes are beneficial for fish and wildlife. They
provide food, dissolved oxygen, and spawning and nesting habitat for fish and
waterfowl. Aquatic plants can trap excessive nutrients and detoxify chemicals.
Aquatic wildflowers such as water hyacinth are sold and planted to provide floral
beauty to garden ponds. However, dense growths of algae and other water plants can
seriously interfere with pond recreation and threaten aquatic life. Invasive aquatic
weeds and abundant nutrients have created many aquatic weed control issues for lakes
and other water bodies. Water weeds can restrict swimming, boating, fishing, and
other water sports. Water weeds can impart unpleasant taste (musty flavor), decaying
vegetation emits offensive odors, and algae can discolor pond waters. Decomposing
water weeds can deplete the oxygen supply, resulting in sport fish kills from
suffocation. Dense plant growths can provide too much cover, preventing predation,
and leading to stunted (small-sized) sportfish populations. Over the years, many
methods have been developed to control aquatic weeds. Mechanical, cultural,
biological and chemical controls are the basic means for aquatic weed control.
Practical Works
Identify and record the weeds from two different localities: landscape/recreational and
water bodies. Take note on the growth of those weeds, associated with the nature. The
activity is to be done in groups, and submit the report individually.
Questions to Answer
1. What are the types of weed species found in garden landscape, recreational ground
and aquatic habitat?
2. Can weeds of landscape areas be the same species as those of aquatic weeds? If
yes, which of those area the same, and why?
3. How do these weeds affect the designated areas that you visited?
Algae: very primitive plants. Some algae are microscopic (planktonic algae), others
are thin and stringy or hair-like (filamentous algae), while still others are large and
resemble higher plants but without true leaves, stems and roots.
Free floating plants: not attached to the water's bottom, with most have roots which
absorb water. The leaves of these plants are firm and remain flat in order to absorb
more sunlight. Floating plants come in sizes from very small (duckweed-Lemna
minor) to over a foot in diameter (water hyacinth).
Marginal plants: also known as shallow water plants, which are found growing
around the edges (margins) of water bodies. Many of them grow upright and share the
need for consistently moist/muddy soil.
Submerged Plants: rooted to the water's floor and most of their vegetation is under
water. The leaves of these plants are usually thin and narrow, while their stems are
soft or flaccid (lack firmness). Example of submerged plants is Hydrilla spp.
Emergent Plants: rooted to the ground of the water but have most of their vegetation
above water. These plants need constant exposure to sunlight. The stems of emergent
plants are somewhat stiff or firm. Example of emergent plants is water lily.