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Using sunflower as an insect trap plant in tomato crops can reduce initial applications to control caterpillars and defoliating beetles (the popular “little cows”) by up to 30%. This happens because the high number of insects that concentrate on sunflower inflorescences and leaves allows for a reduction in these pests in the main crop, requiring less chemical intervention in the crop. Since 2004, the Epagri Experimental Station in Caçador (EECD) has recommended this technique to add to others already used in Integrated Pest Management (IPM) aiming for more sustainable cultivation.
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EECD researcher, Janaína Pereira dos Santos, explains that the use of sunflower as a trap plant is based on the principle that the wavelengths emitted by yellow surfaces attract different species of insects. “The yellow color causes the insect to instinctively search for food, as there is a strong relationship between this color and the presence of pollen grains in the center of the flowers, where the nectar is located. In this way, sunflower can be used to monitor and control insect pests in different types of crops, whose main pests are attracted to the color yellow”, she says.
Several producers in the Alto Vale do Rio do Peixe region who grow tomatoes based on the Integrated Tomato Production System (Sispit) use sunflowers in the crop border. Farmers Valmir and Fabiano Susin, from Caçador, joined Sispit in 2007 and follow Epagri's recommendations to the letter. “Sunflowers are excellent for attracting green cows. Its use allowed the reduction of up to five applications in tomato farming”, says Valmir, who grows six thousand plants of the fruit on half a hectare of the property, maintained in partnership with his brother.
How to do it in practice
The sunflower is only planted on the border of the main crop, as the objective is for it to form a physical barrier for insects, which will feed on the leaves and inflorescences and will not migrate into the crop. It attracts several species of “little cows” of the genera Diabrotica, Paranapiacaba and Microtheca (pest beetles), defoliating beetles of the species Astylus variegatus, whiteflies, mites, inch-long caterpillars, as well as those of the genera Spodoptera and Helicoverpa, which are important tomato pests. Furthermore, it also attracts several natural enemies, such as parasitoid wasps, predators (ladybugs and bedbugs) and pollinating insects (bees and wasps).
Janaína explains that the distance between the sunflower plants will depend on the type of crop. “In tomato cultivation, sunflower seedlings are planted along the entire crop border at a distance of one meter between double rows and 2.4 meters between the main rows. In other crops, sunflower seedlings can be planted closer together, up to one meter apart,” he says.
According to the researcher, the ideal is to transplant the sunflower seedlings a few days after planting the main crop. She points out that the sunflower's vegetative cycle is shorter than that of the tomato plant, therefore, in order to have inflorescences throughout the tomato plant's vegetative cycle, producers must cultivate sunflower seedlings and transplant them in the field two to three times until the completion of the tomato harvest.
If the producer wishes to cultivate sunflower to obtain the crop's other potential, such as selling the grains, extracting oil or even for animal feed, planting can be done in consortium with other crops. “An alternative is to plant a row of sunflowers every two or three rows of the main crop”, recommends Janaína.
Sunflower can be used in various crops on crop borders in order to attract insect pests and natural enemies. As an example, Janaína cites soybeans, beans, peanuts, corn and cruciferous vegetables (cabbage, broccoli, cauliflower, etc.), as they are usually attacked by mites, whiteflies, leafminers, and defoliating beetles of the Astylus species. variegatus, “little cows” of the genera Diabrotica, Paranapiacaba and Microtheca and by inch-long caterpillars, as well as those of the genera Spodoptera and Helicoverpa
The researcher emphasizes that the use of sunflower is just an ally in monitoring and controlling pests in the main crop and warns against high pest infestations. “In these cases, sunflower alone will not be enough to control these populations. Therefore, control must be carried out in the main crop using other strategies that involve chemical or biological control, for example”, he says.
Greenhouse crops
Janaina does not recommend using sunflower as a trap plant in greenhouse crops, as the effect may be the opposite of what is desired, as the closed environment causes pests to remain and multiply inside the greenhouse. “In addition, the temperature and humidity conditions in this type of location can favor the development of several species of pests, such as whiteflies and mites”, warns the researcher.
Environmental awareness
Controlling insect pests exclusively with pesticides is a practice commonly used in commercial agricultural crops. According to Janaína, in many cases these applications are made without technical criteria, which can increase production costs, the risks of environmental poisoning and the presence of residues in food. “Lately, environmental awareness among consumers and farmers has favored the use of more sustainable techniques for pest control,” she says.
Therefore, alternative control methods that are less aggressive to beneficial fauna and the environment must be adopted, which makes it essential to use strategies based on Integrated Pest Management (IPM). In this context, the sunflower is used as a trap plant.
By: Aline Merladete | agrolink
