Integrated weed management in industrial tomato cultivation

Industrial tomato plants have slower initial growth than most weeds, which favors infestation in the early stages of crop development. Changing the system for implementing cultivation areas for transplanting seedlings helps to minimize the problem, however, its control is still challenging. The solution lies in integrated measures in which the use of herbicides is just one of the strategies, used jointly and not in isolation.

Despite the highly technical cultivation of industrial tomatoes, the damage caused by the presence of weeds has been significant, potentially causing losses of 75% in productivity. Considered a demanding crop in terms of fertility, industrial tomato cultivation has been carried out in previously cultivated areas, a fact that raises awareness regarding weed management, since, in these areas, the seed bank in the soil is larger, thus favoring the appearance of several invasive species in the area.

The damage caused by weeds ranges from direct effects such as competition for water, light, nutrients, release of substances with allelopathic effects and indirect effects as hosts of pests and diseases. Weeds such as nutsedge (Cypress round), silk grass (Bermudagrass), jack beans (Canavalia ensiforms), midsection (conyzoid ageratum), black walleye (bidens pilosa) and caruru (Amaranthus deflexus) release allelochemical substances that have an allelopathic effect on the germination and initial development of the tomato plant.

Several species of weeds, such as mastruz (Lepidium virginicum L.), Brassicaceae; joá-de-capote [Nicandra physaloides (L.) Pers.], Solanaceae; black maria (Solanum americanum Mill.), Solanaceae; purslane (Purslane oleracea L.), can also be hosts of diseases such as tomato bacterial wilt (Ralstonia solanacearum), and this fact worsens as these species maintain high populations of these microorganisms in the soil.

The industrial tomato crop has slower initial growth than most weeds, which favors competition from weeds in the early stages of crop development. Therefore, in general, the crop must be kept free from the presence of weeds until 30-45 days, this being the period of greatest interference from these species. This initial competition between the crop and weeds was minimized by changing the system for establishing cultivation areas from sowing in the field to transplanting seedlings produced in trays, which go to the field with four leaves. This cultivation system also provided a greater possibility of chemical control, since the use of pre-emergent herbicides with a residual effect can be managed, which can maintain the initial development without the presence of weeds, with a view to reducing the time of permanence of the crop in the field in the initial stages of development.

Photo: Embrapa Vegetables collection

While demanding crops such as soybeans, cotton, corn, sugar cane, beans and citrus, which are responsible for approximately 85%-90% of the total herbicides consumed in the country, have at their disposal a portfolio of products that provide diverse options In the control of weeds, for tomato cultivation there are currently few options for using herbicides. Chemical control in industrial tomato cultivation is practically restricted to the use of no more than ten molecules distributed for pre- and post-emergence applications of the crop. This situation leads to the need to adopt different strategies in the management of weeds, among which the use of integrated weed management (IMPD) can be highlighted.

Integrated Management

Integrated Weed Management (IMPD) aims to integrate several control methods (preventive, cultural, mechanical and chemical), to guarantee the premise of quality of the harvested product, including the absence of pesticide residues in food; environmental sustainability, avoiding soil degradation and air and water contamination; economic and social sustainability in production, maintaining or increasing productivity; and the guarantee of a better quality of life for the farmer in terms of economic return and greater safety in activities that involve the use of agricultural pesticides. A good weed management program must allow maximum production in the shortest amount of time, maximum production sustainability and minimum economic and environmental risk. To do this, the producer must know the competitive capacity of the weed species present in his area and use different control strategies that best adapt to his reality.

preventive control

Preventive control aims to prevent the entry and establishment of weeds in areas not yet infested. It is the responsibility of each farmer to prevent the entry and spread of one or more weed species that could become serious problems on their property and region. Among the preventive measures that can be adopted, we can mention: carefully sanitizing agricultural machinery and implements; clean irrigation canals; acquisition of certified seeds; production of seedlings in contamination-free substrates, etc.

The lack of such care has caused widespread dissemination of the most diverse species, such as nutsedge (Cyperus spp.), which has very small seeds and tubers that infest new areas very easily, through manure, substrate. To disinfest substrates, solarization can be used, which is a hydrothermal process that sterilizes the soil through naturally generated heat. Solarization acts on plant seeds or propagules through the direct action of heat and humidity, burning germinated seedlings and changing gas balances, affecting plant germination.

Cultural control

Cultural control can be understood as cultural practices that favor the development of crops to the detriment of weeds. Among these practices, the planting of cultivars adapted to the region stands out; the use of treated seeds, with a high germination and vigor rate; the transplantation of well-formed seedlings, at a time favorable to the development of the crop; adequate soil preparation; balanced fertilization, etc. In addition to these cultural practices, the adoption of crop rotation and direct planting has proven to be an extremely interesting tool in the management of weeds in tomato crops.

crop rotation

Rotation breaks the cycle of weed species, preventing their dominance in the area. When the same cultural techniques are applied repeatedly, year after year, on the same soil, the interference of certain weeds tends to increase significantly. With crop rotation, the dynamics of weeds changes and with it control methods also change, especially herbicides with different spectrums of action. The choice of crop for rotation should be based on plants with very contrasting growth habits and cultural characteristics. Crops planted in succession should preferably belong to botanical families other than tomato (Solanaceae), so you should avoid planting crops such as potatoes, peppers, peppers and eggplants in succession, for example. Efficient control of spontaneously occurring tomato plants in rotational cropping is also very important.

no-till

Failure to disturb the soil and maintaining mulch on the surface affect the dynamics of the weed community. Maintaining straw on the surface can hinder the emergence of seedlings (physical barrier), inhibit the germination of positive photoblastic seeds, release allelochemical compounds that negatively affect the germination and development of weeds, in addition to favoring the activity of microorganisms responsible for elimination of dormant seeds through deterioration and loss of viability. However, it is worth highlighting that direct planting tends to favor the development and increase of perennial weed species, which are less observed in the conventional planting system.

Mechanical control

Mechanical control consists of the use of weed elimination practices, whether by animal, human or tractor traction. Control occurs through the mechanical effect of breaking, pulling out and exposing plant structures to drying by the sun. Despite being an efficient method, in soil with low humidity, it requires a lot of labor and has a high cost, which is why it is generally used in a complementary manner. Furthermore, continuous soil disturbance can favor the multiplication of weed species that propagate vegetatively, such as trapoeraba (Commelina spp.) and nutsedge. Mechanical control can cause damage to the tomato root system due to the fact that the crop has a very branched root system, with roots close to the surface. In this way, weeding can create entry points for phytopathogenic microorganisms, in addition to stimulating the occurrence of stylar rot (Ca deficiency).²⁺), considering that absorption of this nutrient by the roots may be impaired. The use of cultivators is restricted to the initial phases of the crop and promotes weed control only between the rows, with control in the planting rows being carried out manually.

chemical control

Currently, chemical control is the method most adopted by tomato producers. However, it is important to highlight that the herbicide is a chemical molecule that must be handled carefully to avoid the risk of contaminating the applicator. Inappropriate use of this product can also cause environmental pollution: water (rivers, lakes and groundwater), soil and food, which is why there is a need for specialized labor to apply the herbicide, which is the main cause of problems encountered in practice. To correctly use herbicides, it is necessary to have knowledge of the physiology of plants, the groups to which the herbicides belong, and the application technology. Compliance with these details is of fundamental importance for the success of chemical control of weeds.

Herbicides registered for tomato cultivation

Currently, there are seven active ingredients and ten herbicides registered for use in tomato crops (Table 1). The tomato plant is characterized by being a plant susceptible to the action of herbicides, mainly post-emergent ones used to control dicotyledonous weeds. With the exception of metribuzin and flazasulfuron, the other herbicides used in the crop are for narrowleaf control (Table 2). Therefore, it is possible to infer that broadleaf control is more problematic, often requiring complementation with the mechanical control method to keep the crop free from the occurrence of weeds during its critical period.

It is important that the producer understands that chemical control should only be used as a complementary method. Cultural control is of greater importance, as it allows for the best conditions for crop development, providing a competitive advantage over the infesting community. Chemical management as the only control method can lead to imbalance in the production system. Therefore, herbicide should be viewed as just another tool in MIPD. The choice of control methods must be appropriate to the reality of each property, depending on the available resources, the species present in the area, the topography, the machinery and the cultural level of the producer.

Creeping tomato in Brazil

The cultivation of creeping tomatoes generates the main raw material for the tomato industry, known as industrial tomatoes. Industrial tomato production in Brazil in the last harvest (2012) was approximately 1,2 million tons, a drop of 25% compared to the previous harvest. This scenario means that Brazil is not self-sufficient in the production of industrial tomatoes, having to import the raw material (pulp or fruit paste) for the industry from countries such as Chile and China.

While the per capita consumption of industrial tomatoes has grown in recent decades, driven mainly by the growth of fast food chains, in recent years the production of industrial tomatoes in Brazil has suffered several fluctuations, which can be attributed mainly to climatic conditions. However, in addition to the climate, there is the interference of pests, diseases and weeds.

Table 1 - Commercial products registered with the Ministry of Agriculture, Livestock and Supply (Mapa) for use in tomato cultivation

Commercial Product1	Active ingredient	Concentration	Application method2	Dose (kg or L ha-1) Commercial product	Toxicological class	environmental class	Registrant
Lord	clethodim	240 g / L	POST	0,35 to 045	I	III	Arysta LifeScience do Brasil Chemical and Agricultural
Select 240 EC	clethodim	240 g / L	POST	0,35 to 045	I	III	Arysta LifeScience do Brasil Chemical and Agricultural
katana	flazasulfuron	250 g / kg	PRE & POST	0,2 to 0,4	IV	III	Isk Biosciences do Brasil Agricultural Pesticides
Fusilade 250 EW	fluazifop-p-butyl	250 g / L	POST	0,5 to 0,75	III	II	Syngenta Crop Protection LTDA
Bunema 330 CS	metam-sodium	383 g / L	PRE	750	II	I	Taminco do Brasil Produtos Químicos LTDA
Sencor 480	metribuzin	480 g / L	PRE & POST	1,0	IV	II	Bayer SA
Soccer SC	metribuzin	480 g / L	PRE & POST	1,0	IV	II	Bayer SA
Targa 50 EC	quizalofop-p-ethyl	50 g / L	POST	2,0	I	II	Arysta LifeScience do Brasil Chemical and Agricultural
Premerlin 600 EC	trifluralin	600 g / L	PPI & PRE	0,9 to 4,0	I	II	Milenia Agrociências SA
Nortox Trifluralin	trifluralin	445 g / L	PPI & PRE	1,2 to 2,4	II	II	nortox SA

Commercial Product¹

Active ingredient

Concentration

Application method²

Dose (kg or L ha^-1) Commercial product

Toxicological class

environmental class

Registrant

Lord

clethodim

240 g / L

POST

0,35 to 045

I

III

Arysta LifeScience do Brasil Chemical and Agricultural

Select 240 EC

clethodim

240 g / L

POST

0,35 to 045

I

III

Arysta LifeScience do Brasil Chemical and Agricultural

katana

flazasulfuron

250 g / kg

PRE & POST

0,2 to 0,4

IV

III

Isk Biosciences do Brasil Agricultural Pesticides

Fusilade 250 EW

fluazifop-p-butyl

250 g / L

POST

0,5 to 0,75

III

II

Syngenta Crop Protection LTDA

Bunema 330 CS

metam-sodium

383 g / L

PRE

750

II

I

Taminco do Brasil Produtos Químicos LTDA

Sencor 480

metribuzin

480 g / L

PRE & POST

1,0

IV

II

Bayer SA

Soccer SC

metribuzin

480 g / L

PRE & POST

1,0

IV

II

Bayer SA

Targa 50 EC

quizalofop-p-ethyl

50 g / L

POST

2,0

I

II

Arysta LifeScience do Brasil Chemical and Agricultural

Premerlin 600 EC

trifluralin

600 g / L

PPI & PRE

0,9 to 4,0

I

II

Milenia Agrociências SA

Nortox Trifluralin

trifluralin

445 g / L

PPI & PRE

1,2 to 2,4

II

II

nortox SA

¹ Read and follow the leaflet recommendations made by the Companies; ²PPI: pre-planting incorporated between 5cm and 10cm; PRE: pre-emergence; POST: post-emergence

Source: Adapted Map (2013)

Table 2 - List of registered species with the possibility of using chemical control in tomato cultivation (Mapa, 2013)

Species	Lord	Select 240 EC	katana	Fusilade 250 EW	Bunema 330 CS	Sencor 480	Soccer SC	Targa 50 EC	Premerlin 600 EC	Nortox Trifluralin
Brachiaria plantaginea	X	X	X	X				X	X	X
Cenchrus echinatus	X	X	X	X	X			X	X	X
Digitaria horizontalis	X	X	X	X				X		X
Digitaria insularis	X	X								X
Echinochloa crusgalli	X	X							X	X
Eleusine indica	X	X		X	X			X	X	X
Eragrostis ciliaris	X	X
Oryza sativa	X	X		X
Panicum maximum	X	X							X	X
Pennisetum americanum	X	X
Pennisetum setosum	X	X							X	X
Rottboellia exaltata	X	X
Setaria geniculata	X	X
Sorghum halepense	X	X							X	X
Triticum aestivum	X	X		X
zea mays	X	X		X
conyzoid ageratum							X
Alternanthera tenella						X	X			X
Amaranthus hybridus					X	X	X		X	X
Amaranthus viridis			X			X	X		X	X
bidens pilosa			X		X	X	X
Desmodium tortuosum						X	X
Emilia sonchifolia							X
Galinsoga parviflora						X	X
Hyptis lophanta						X	X
Ipomoea aristolochiaefolia						X	X
Nicandra physaloides						X	X
Phyllanthus tenellus						X	X
Portulaca oleracea			X		X	X	X		X	X
Raphanus the radish			X			X	X
Richardia brasiliensis						X	X
Coronopus didymus						X
Emilia sonchifolia						X
Polygonum convolvulus						X
Senecio brasiliensis						X
Sida rhombifolia					X	X
Sonchus oleraceus						X
Spergula arvensis						X
Spermacoce latifolia						X
Acanthospermum hispidum			X
Brachiaria decumbens			X						X
Cypress round			X
Bermudagrass				X
Commelina benghalensis					X
Brachiaria platyphylla									X
Digitaria ciliaris									X
Digitaria sanguinalis									X
Echinochloa colona									X
silene gallica									X	X
Spergula arvensis									X
Bromus catharticus										X
Mollugo verticillata										X
Panicum dichotomiflorum										X
Creeping bluegrass										X
Bicolor sorghum										X
Urtica circularis										X
Source: Adapted Map (2013)

Species

Lord

Select 240 EC

katana

Fusilade 250 EW

Bunema 330 CS

Sencor 480

Soccer SC

Targa 50 EC

Premerlin 600 EC

Nortox Trifluralin

Brachiaria plantaginea

X

X

X

X

X

X

X

Cenchrus echinatus

X

X

X

X

X

X

X

X

Digitaria horizontalis

X

X

X

X

X

X

Digitaria insularis

X

X

X

Echinochloa crusgalli

X

X

X

X

Eleusine indica

X

X

X

X

X

X

X

Eragrostis ciliaris

X

X

Oryza sativa

X

X

X

Panicum maximum

X

X

X

X

Pennisetum americanum

X

X

Pennisetum setosum

X

X

X

X

Rottboellia exaltata

X

X

Setaria geniculata

X

X

Sorghum halepense

X

X

X

X

Triticum aestivum

X

X

X

zea mays

X

X

X

conyzoid ageratum

X

Alternanthera tenella

X

X

X

Amaranthus hybridus

X

X

X

X

X

Amaranthus viridis

X

X

X

X

X

bidens pilosa

X

X

X

X

Desmodium tortuosum

X

X

Emilia sonchifolia

X

Galinsoga parviflora

X

X

Hyptis lophanta

X

X

Ipomoea aristolochiaefolia

X

X

Nicandra physaloides

X

X

Phyllanthus tenellus

X

X

Portulaca oleracea

X

X

X

X

X

X

Raphanus the radish

X

X

X

Richardia brasiliensis

X

X

Coronopus didymus

X

Emilia sonchifolia

X

Polygonum convolvulus

X

Senecio brasiliensis

X

Sida rhombifolia

X

X

Sonchus oleraceus

X

Spergula arvensis

X

Spermacoce latifolia

X

Acanthospermum hispidum

X

Brachiaria decumbens

X

X

Cypress round

X

Bermudagrass

X

Commelina benghalensis

X

Brachiaria platyphylla

X

Digitaria ciliaris

X

Digitaria sanguinalis

X

Echinochloa colona

X

silene gallica

X

X

Spergula arvensis

X

Bromus catharticus

X

Mollugo verticillata

X

Panicum dichotomiflorum

X

Creeping bluegrass

X

Bicolor sorghum

X

Urtica circularis

X

Source: Adapted Map (2013)

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