Chemicals - STOMP

INTRODUCTION

Research and development work carried out by the American Cyanamid Company (American Cyanamid in turn, being acquired by BASF in 2000) led to the discovery and development of STOMP® 330E Herbicide. Trial work in Australia in the late 1970’s saw the introduction of STOMP to the market in Australia.

STOMP contains pendimethalin, a selective dinitroaniline (DNA) herbicide that effectively controls a broad spectrum of annual grasses and broad-leaved weeds in many important broadacre and horticultural crops as well as turf and forestry.

The primary mode of action of STOMP is to stop plant cells dividing and elongating in susceptible species. Best control of target weeds is achieved by application to soil prior to germination and before weeds emerge. Weeds die shortly after germination or soon after emergence from the soil. STOMP has some limited post-emergence activity on broad-leaved weeds. STOMP does not control perennial or well-established weeds.

The relatively low volatility and photodecomposition of STOMP allows flexibility in application techniques. STOMP is effective when applied via pre-plant incorporation (double incorporation), incorporated by the sowing process, or post-plant pre-emergence (non mechanical incorporation) at dosages ranging from 0.75 to 12L/ha, depending on the crop, the method of application, the soil type and organic matter content, and the weed spectrum. Crop safety often depends on application method and rate used, so it is VERY IMPORTANT TO CHECK THE LABEL USE CONDITIONS.

STOMP alone, and in combination with other herbicides, is registered for use in over 60 countries in more than 70 crops. Weed control in cereals, canola, rice, maize, sunflower, cotton, sugarcane, vegetables, plantation crops, and other agronomic and horticultural crops has been outstanding.

Significant trial data has been compiled over many years relating to the chemical properties of STOMP, particularly in the 1970’s. Recent data is crop specific, testing modern agronomic use patterns and crops.

SUMMARY OF STOMP BENEFITS

STOMP controls a wide range of grass and broad-leaved weeds including annual ryegrass and wireweed.
STOMP can be used in a range of crops including broadacre and rotational crops, horticulture and other speciality markets.
STOMP provides residual control of weeds as they germinate and emerge.
STOMP can be applied on the ground of from the air.
STOMP is extremely flexible – it can be incorporated up to 24 hours after spraying and applied right up to the time of sowing. Even the method of incorporation is flexible – choose from mechanical, irrigation or rainfall.
STOMP has relatively low volatility and is extremely photo-stable.
STOMP is safe on crops and offers minimal crop pruning.
STOMP has a wide range of compatibility with other herbicides.
STOMP is available in 20 litre drums, 100 litre AGRETURN containers and in bulk.
STOMP is the ideal product to use in an integrated weed management strategy as a tool for delaying the onset of weed resistance.
STOMP is environmentally sound, and less likely to leach than the triazines or trifluralin.

MODE OF ACTION

STOMP disrupts cell division and cell elongation in shoot and root meristems of susceptible plants. Germination of plants is unaffected by the herbicide; growth inhibition and subsequent death occur following germination of the seed or shortly after emergence from the soil.

Typical symptoms of the aerial parts of susceptible dicot (broadleaf) weed plants that emerge include severe stunting, intense green colouration, and a leathery appearance of the cotyledons. Monocot (grass and sedge) plants that emerge are stunted and twisted and show a red-purple colouration. Root effects are observed as a characteristic swelling of the tip. Shoot-growth inhibition occurs in susceptible monocots after absorption by the coleoptilar node, when this meristematic region is in contact with or passes through the area treated with pendimethalin. In dicots, the hypocotyl or hypocotyl hook is the most sensitive site of absorption. Root growth is affected when the root meristem absorbs the herbicide from the soil; however, plant kill occurs only when the shoot meristem of monocots or dicots contacts the herbicide and growth is severely disrupted. Effect on the shoot from the root absorption is a secondary effect, since translocation from root to shoot is minimal.

The primary site of action of STOMP is the growing points of a plant. Because STOMP does not translocate a great deal from the site of uptake, it is necessary for the emerging seedling to absorb pendimethalin from the soil (i.e. Following pre-plant incorporated or pre-emergence applications). An alternative is for pendimethalin to be applied directly to the meristematic region of the plant. Differential susceptibility is caused by differences in germination depth and exposure of growing points to direct applications.

The mechanism of action of pendimethalin involves inhibition of microtubule formation in cells. This causes disruption of cell division as the microtubule spindle fibres that guide chromosomes are absent, the cell plate does not appear and cells do not divide.

The microtubules are also responsible for microfibril orientation in the cell wall; in their absence, microfibrils become disoriented and cells expand to a rounded rather than elongated shape.

Generally, incorporation of STOMP will increase activity against monocot weeds by allowing absorption at the sensitive shoot meristem (the coleoptile node) and the root meristems. Effectiveness on dicot species can be reduced by incorporation because of dilution of the herbicide in the soil profile; in this case, the concentrated band near the soil surface will have greater effect through its action on the most sensitive site, the hypocotyl. Thus, the herbicidal effect of STOMP varies according to the relative location of the sensitive meristems and herbicide placement in the soil. This is also a major factor in the tolerance of certain crops to STOMP.

TOLERANCE

SEEDED CROPS

Tolerance to STOMP may be “physiological” or “positional”. In the case of physiological tolerance, crops can be sown safely in soil treated with STOMP pre-plant incorporated (e.g. cotton, soy beans, sunflowers, peanuts, carrots and peas). A high-lipid content in the seed is generally associated with and may explain the higher degree of tolerance of these crops compared to susceptible weeds.

In the case of positional tolerance, the seed is placed below the herbicide layer. Thus, the sensitive meristem should not come in contact with the herbicide layer. This applies, for example, when treating cereals, rice, maize, onions, potatoes and most vegetables.

Phytotoxicity can occur:

a. when the seed is won too shallow and the shoot and root meristems come into contact with the herbicide;
b. when heavy rain following treatment of light soils moves the herbicide and soil particles, to which the herbicide is absorbed, down to the seed level.

TRANSPLANTED CROPS

STOMP may be applied to the soil before transplanting crops such as brassicas, as a surface or incorporated treatment without causing phytotoxicity. No treated soil should reach the roots of the seedling during planting.

BEHAVIOUR IN THE SOIL

SOIL pH

Soil pH has minimal effect on performance or degradation of STOMP.

SOIL LEACHING

Chemical hydrolysis is the most important degradation pathway for STOMP. Hydrolysis is maximised under warm moist conditions.

Entry of leachates into the soil is characterised by higher initial infiltration rates which decrease rapidly as soil moisture saturation is approached. Dry soils have higher initial rates of infiltration than wet soils, thus the potential for herbicide movement is greatest when crops are planted dry and watered.

A herbicide with lower solubility has less potential for movement in the soil than a herbicide with higher solubility. STOMP has significantly lower solubility than many other commonly used pre-emergence herbicides and is considered to have extremely low leachability.

Water solubility figures for several commonly used pre-emergence herbicides are given below:

STOMP is the least water soluble, therefore reducing the potential for leaching. STOMP is strongly absorbed to soil, therefore the potential for runoff or leaching is minimised. Organic carbon content of the soil has the largest impact on the absorption of STOMP.

VOLATILISATION

The degree of loss of a herbicide from volatilisation is related to its vapour pressure. Herbicides with higher vapour pressures are subject to higher potential losses from volatilisation than those with lower vapour pressures. Although STOMP has a measurable vapour pressure, its strong binding to soils helps to reduce its potential loss through volatilisation. Laboratory studies have demonstrated that volatilisation is not a major route in the dissipation of STOMP from the soil.

Incorporating the herbicide into the soil can control volatilisation losses. The volatility of herbicide will influence its incorporation requirements and hence the degree of flexibility available to the grower at the time of application.

** The time period required for incorporation of STOMP is related to herbicide rate applied. An incorporation requirement of 7 to 10 days relates to use of STOMP at 4.5 l/ha applied immediately after sowing cotton

Trifluralin is approx 4 times more volatile than STOMP

STOMP can be incorporated by Mechanical means, rainfall or irrigation can incorporate STOMP. Once incorporated, volatilisation of STOMP is minimal.

Though chemically related and having a similar range of uses, STOMP and trifluralin differ in their chemical and biological properties, which affects weed control spectrum, crop safety and application requirements.

Harvey (1974), studies of DNA herbicides, found the activity of these herbicides to be directly related to their volatility. It is recognised that high levels of volatility can contribute to the poor performance of DNA herbicides.

Activity remaining after delayed incorporation:

Trifluralin is more volatile than STOMP, which means greater losses from the soil can be expected if soil incorporation is delayed or poorly carried out. The following table from Kennedy and Talbert (1977) illustrates a loss of chemical activity with trifluralin relative to STOMP as soil incorporation is delayed.

IMPACT OF SOIL MOISTURE ON VOLATILITY

Losses due to volatility are related to soil moisture. Kennedy and Talbert (1977) have found that as soil moisture increases, absorption decreases and surface loss greatly increases.

STOMP is affected to a much less degree by the soil moisture content than trifluralin. This is shown below:

ROOT INJURY

Root injury to crops has been observed when using some DNA herbicides. Numerous investigations have shown lateral root inhibition when using trifluralin on wheat, maize, cotton, peanuts, tomatoes, peas and a large range of other crops. Root injury by STOMP has been shown to be much less significant or non-existent. Gordon and Frans (1977) have ranked the DNA herbicides according to lateral root inhibition:

trifluralin greatest root inhibition;
pendimethalin (STOMP) least root inhibition.

PHOTODECOMPOSITION

Herbicide loss also occurs by photodecomposition. This is the breakdown of a chemical induced by the absorption of light energy. Results of a laboratory experiment comparing the rates of photodecomposition for STOMP and trifluralin are summarised below:

Rate of Photodecomposition:

When applied at 4.5L/ha immediately after sowing, incorporation of STOMP within 7 to 10 days will result in minimal loss from photodecomposition and volatilisation.

Helling (1976) has shown STOMP to be less prone to photodecomposition than trifluralin. It was found that after 6 days exposure to sunlight, losses due to photodecomposition were:

STOMP – 2-9% applied was lost
Trifluralin – 10-15% applied was lost.

The registered claims for trifluralin require an incorporation within four hours of application due to its volatility and photodecomposition. Incorporation of STOMP is recommended within 24 hours to 10 days of application.

CROP SUMMARY LIST
All crops/situations in which STOMP is registered:

BROADACRE / ROTATIONAL CROPS

HORTICULTURE

SPECIALTY / OTHER

Barley	Avocadoes	Eucalypts
Canola	Bananas	Irrigation channels
Chick peas	Broad beans	Lucerne
Cotton	Broccoli	Maize
Cow peas	Cabbage	Pyrethrum
Faba beans	Carrots	Rice
Field peas	Cauliflower	Sugarcane
Lupins	Citrus	Teatree
Mung beans	Deciduous fruits	Turf
Navy beans	French beans
Peanuts	Grapevines
Pigeon peas	Lettuce
Safflower	Lychees
Soy beans	Macadamia nut
Sunflowers	Mangoes
Wheat	Nuts
	Onions
	Processing peas

WEED SUMMARY LIST
Weeds controlled by STOMP:
Weeds that are suppressed by STOMP are marked with an *

Annual Nettles*	Fat Hen	Scarlet Pimpernel
Annual Ryegrass	Fumitory*	Shepherd's Purse
Asthma Plant	Green Amaranth	Silvergrass*
Awnless Barnyard Grass	Green Fat Hen	Silvertop Grass
Barnyard Grass	Green Summer Grass	Sowthistle
Bittercress	Guinea Grass	Sowthistle
Blackberry Nightshade*	Indian Hedge mustard*	Stagger Weed*
Bladder Ketmia	Liverseed Grass	Stink Grass
Brigalow Grass	Mexican Clover (white eye)	Summer Grass
Button Grass	Mintweed*	Turnip Weed*
Caltrop*	Mossman River Grass	Weeping Love Grass
Chickweed	Native Millet	Wild Oats*
Common Heliotrope	Pale Pigeon Grass	Wild Radish*
Common Sowthistle*	Peppercress*	Winter Grass*
Common Verbena*	Pepper Grass	Wireweed
Crested Goosefoot	Pigeon Grass
Crowsfoot Grass	Pigweed
Deadnettle	Prickly Lettuce
Dwarf Amaranth	Queensland Blue Grass
Early Spring Grass	Red Flinders Grass

GENERAL INSTRUCTIONS

ALWAYS READ THE LABEL THOROUGHLY BEFORE USING THE PRODUCT

STOMP is a selective herbicide for the control of most annual grasses and certain broad-leaved weeds. STOMP controls weeds by inhibiting seedling development; it will not control established weeds. For best results, seedbeds should be free of weeds, trash and clods at the time of application.

Soils containing a high percentage of organic matter can result in poor control. It is recommended that application to soils containing a high percentage of organic matter (greater than 6%) be avoided.

Crop injury may result if cold, wet weather follows planting or it STOMP is applied to a poorly prepared seedbed. With the return of favourable growing conditions (warm weather), the crop will usually recover and resume normal growth.

STOMP will stain (yellow) any objects it contacts, so avoid contact with objects you do not want stained.

MIXING

Place half the required volume of water in spray tank and start agitation. When using alone, add STOMP to partially filled tank and then add the remainder of the water. Mix thoroughly.

When using STOMP in tank mixes with products such as atrazine or diuron, mix these products as indicated on the relevant label and add the STOMP last, then complete filling of the tank.

Maintain good agitation at all times until spraying is completed. If the spray mixture is allowed to settle, thorough agitation is essential to re-suspend the mixture before spraying is resumed. Note that when tank-mixing STOMP with paraquat and glyphosate herbicides, the STOMP should be thoroughly mixed in the spray tank first, before adding a paraquat or glyphosate product.

APPLICATION METHOD

GROUND APPLICATION

Use conventional sprayers with either mechanical or by-pass agitation. Flat fan nozzles should be used. Spray equipment should be correctly calibrated to ensure proper application. If applying STOMP in tank mix combination with atrazine or diuron, nozzle screens must be no finer than 50 mesh. Apply the recommended quantity of STOMP in 50-200 litres of water per hectare. Where pre-emergence surface treatment is used, the higher rates of water are recommended.

AERIAL APPLICATION

Pre-plant soy beans, cotton, sunflowers, peanuts, navy beans, cow peas, mung beans, pigeon peas and post-plant, post flushed combine sown rice only.

Apply the recommended quantity of STOMP in 25-60 litres of water per hectare. It is essential that the equipment is correctly calibrated and an even spray pattern is obtained. It is also essential that an accurate swath width is maintained. Do NOT apply if wind speed is greater than 16km/h. Always spray with a crosswind in accordance with recommended flying practice.

Do NOT apply STOMP 330E Herbicide by aerial spraying in eucalypt forestry situations.

INCORPORATION

Incorporation can be critical for crop tolerance and weed control. Always read the label or see label directions for use.

a. STOMP works best if thoroughly mixed with soil either mechanically or by irrigation or rainfall. The aim of incorporation is to produce an even band of herbicide to intercept germinating weed seeds. The earlier this occurs the better, but incorporation within 7-10 days after application of a 4.5L/ha rate applied immediately after sowing is satisfactory. Unlike trifluralin, the incorporation process is not urgent. This is due to the relatively low volatility and greater light stability of STOMP.

The movement of pre-emergence herbicide in the soil can affect its potential efficacy on weeds and its crop safety. Retention of herbicides in the surface layers of soil is often important for crop selectivity.

b. Post-plant pre-emergence surface applications of STOMP alone, or as a tank mixture, are most effective in controlling weeds when adequate rainfall occurs or irrigation is applied within 7-10 days after treatment to achieve incorporation. If no rain or irrigation is received within 7-10 days, light mechanical incorporation is required for optimum weed control, except when used on maize, carrots and rice.
c. Maize is tolerant to STOMP either alone or in mixtures with atrazine if the seed germinates below the chemically treated band. Maize, carrots and rice are NOT tolerant to STOMP if it is in direct contact with the seed.

Compatibility

Physical compatibility of STOMP has been tested with the following herbicides:

ametryne, atazine, diuron, fluometuron, fluometuron plus prometryne, glyphosate (Roundup), linuron, paraquat (Gramoxone), prometryne, propanil, Ramrod Flowable, Logran, simazine.

FOLLOWING CROPS

In the event of crop failure, the soil should be cultivated to a minimum depth of 15cm to ensure any residues are evenly dispersed throughout the soil. If a maize crop fails due to weather conditions or some other reason, maize can be replanted the same year without adverse effects but seeding depth must be below the re-tilled area.

Carrots, parsnips, parsley, celery, potatoes, peas, french beans, transplanted brassicas, transplanted lettuce, transplanted tomatoes and transplanted capsicums may be sown after a minimum interval of 2 months after application of STOMP.

Turnips, lettuce, radish, brussel sprouts, cabbage, cauliflower, broccoli, onions, leeks, sweetcorn, pumpkins, squash, melons and cucumbers may be sown after a minimum interval of 5 months after application of STOMP.

Redbeet(beetroot), spinach, silverbeet and poppy may be sown after a minimum interval of 12 months after application of STOMP.

RESISTANCE

Herbicide resistance has become a major issue in Australian agriculture since it was first reported in annual ryegrass in 1982. It is the inherent ability of certain individuals to survive a normally lethal dose of a herbicide. This means that the herbicide has no effect on controlling these resistant individuals, leading to reduced crop yields from failing to eliminate weed competition. Herbicide resistance may be minimised by rotating herbicide mode of action groups and undertaking other cultural weed seed minimisation practices i.e. Integrated Weed Management.

Herbicides act by interfering with specific processes in plants – this is their mode of action. Herbicide product labels carry letter codes representing their specific mode of action group.

STOMP is a member of the dinitroaniline group of herbicides. For weed resistance management, this group is a GROUP D HERBICIDE. It has the inhibition of tubulin formation mode of action. This has a totally different mode of action from the “fop”, “dim” (Group A) and sulfonylurea (Group B) herbicides. These A and B groups have single site mode of action, and resistance to these herbicide groups is more prevalent than to Group D.

Some naturally occurring weed biotypes, resistant to STOMP and other Group D herbicides, may exist through normal genetic variability in any weed population. These individuals can eventually dominate the weed population if similar mode of action group herbicides are used repeatedly. These resistant weeds will not be controlled by STOMP or other Group D herbicides.

Since the occurrence of resistant weeds is difficult to detect prior to use, BASF Australia Ltd accepts no responsibility for any losses that may result from the failure of STOMP to control resistant weeds.

It is important to rotate between herbicide mode of action groups across years to reduce the likelihood of resistance. BASF Australia Ltd recommend referring to the AVCARE Herbicide Resistance leaflet, for suggested Integrated Weed Management Strategies.

SAFETY AND THE ENVIRONMENT

In order to protect crops, native plants and other non-target plants, do NOT apply STOMP under meteorological conditions or from spraying equipment which could be expected to cause spray to drift onto nearby susceptible plants, adjacent crops, crop lands or pastures.

STOMP is extensively metabolised in plants and animals to a number of degradation products through a series of complex processes. This biotransformation proceeds rapidly in animals but more slowly in plants.

STOMP is non-toxic to birds, soil microflora, wild animals and bees. It rapidly degrades under anaerobic conditions in aquatic environments.

Always remember STOMP is dangerous to fish and other aquatic life. Do NOT contaminate dams, rivers, drains or streams with chemical or used containers.

STORAGE AND DISPOSAL

Store STOMP in the closed, original container in a cool, well-ventilated area. DO NOT store for prolonged periods in direct sunlight. DO NOT dispose of undiluted chemicals on-site.

The method of disposal of the container depends on the container type. Read the “Storage and Disposal” instructions on the label that is attached to the container.

SAFETY DIRECTIONS AND FIRST AID

STOMP is harmful if swallowed. It will irritate the eyes, throat, nose and skin, so avoid contact. When preparing spray and using the prepared spray, wear face shield or goggles and rubber gloves. If the product gets in eyes, wash it out immediately with water. After use and before eating, drinking or smoking, wash hands, arms and face thoroughly with soap and water. After each day’s use, wash gloves and face shield or goggles. If poisoning occurs, contact a doctor or Poisons Information Centre. Telephone 131126 Australia-wide. If swallowed do NOT induce vomiting. Give a glass of water.

The information contained in these pages is intended as a general guide only. Chemical products are constantly changing in formulation, strength of active ingredients, registered uses and withholding periods - ALWAYS READ THE PRODUCT LABEL CAREFULLY AND USE PRODUCTS ONLY ACCORDING TO LABEL DIRECTIONS AND ONLY ON THOSE CROPS OR USES AS SPECIFIED ON THE LABEL.