TOP 6 main questions and answers about the sunflower broomrape

Sunflower is a culture that is highly valued by Ukrainian agricultural producers. In recent years, the crop acreage of sunflower is more than 6,000,000 hectares. According to scientists, about 70% of these crops are affected by the sunflower broomrape (Orobance Cumana). Depending on the region, the infection has different degrees and is caused by different races. Wherever the sunflower broomrape appears, especially its new aggressive races, it causes significant crop losses.

For this reason, the scientific conference, which was devoted to the problem of the sunflower broomrape, took place as part of the exhibition "Agroexpo-2018". This conference was held by the company "Eurosem". It was of the most immediate interest and gathered a large audience of listeners.

“Does the sunflower broomrape spread through seed material?” Why do new and more aggressive races of the broomrape appear every year? Which of the known measures for control of the parasites are actually effective? Which measures can only worsen the situation?” These and many other issues were discussed at the conference. In this article the website farmerscan.com will highlight the most essential issues.

Question №1: What is the reason for the imminent appearance of new races and the formation of local races of the broomrape?

The answer to this question lies in understanding the ways of reproduction of this parasite. Nowadays the reproduction occurs in three ways:

1. self-pollination – up to 80%;

2. cross-pollination – up to 20%;

3. apomixis – up to 1% (reproduction, which is not accompanied by the sexual process).

"At the beginning of its existence the broomrape was at 100% self-pollinate culture. For this reason, the appearance of new races was very slow. In fact, new races had appeared only every 20-40 years. But eventually, due to some mutations, cross-pollination appeared. Up to 20% of seeds appear by the way of cross-pollination. Moreover, the pollination happens not only to plants of the same species, but also to plants of different species and genera. Over the last 5-7 years, up to 1% of all seeds, were formed by the way of apomixis. This is actually a cloning, which leads to various kinds of genetic differences, and contributes to mutations”, shared Dmytryi Shatsman, director of the company "Eurosem".

Thus, reproduction in three ways ensures the formation of new aggressive races in a relatively short period of time:

“That is why nowadays those races of the broomrape that we know such as Turkish or Spanish, are local. Now we can even talk about local races within one region, within a radius of two hundred kilometers. A separate population goes its own way of development and produces the most successful plants", – summed up Dmytryi Shatsman.

Question № 2: What are the types of sunflower resistance to the broomrape?

The sunflower resistance to the broomrape is an effective method of dealing with this problem. The donors of resistance genes in selection and seed production are annual and perennial forms of wild sunflower.

Depending on the method of counteraction, there are several types of resistance:

1. The root tumor was identified on hybrids, which are resistant to the race A. This is due to the hyperfunction of the bark and wood. In the place of germination of the broomrape, a lignified knob is formed, which prevents further damage.

2. The next type of resistance lies in the change of the chemical composition of root secretions. By the absence of substances, which are necessary for germination in the soil, the broomrape does not develop that is peculiar for the resistance against race B.

3. The principle of hypersensitivity reaction lies in the death of root cells at the point of contact with the broomrape. On the dead parts of the root, the parasite cannot develop and will die out. It is also found on hybrids, which are resistant to the race B.

4. During the penetration of the broomrape to the vascular system, a layer of lignin (hardener) is formed in the plant, which blocks further growth of the parasite. The phenomenon is characteristic for hybrids, which are resistant to the race C.

Question № 3: How relevant is the concept of tolerance of sunflower to the broomrape?

By tolerance is meant the ability of a plant to grow and develop normally at a certain level of damage. Some hybrids and sunflower varieties can exist even by the broomrape parasitizing on a certain number of plants. According to the reaction to the parasitic plant, the sunflower is conditionally divided into sensitive, moderately sensitive and insensitive. By the broomrape damage, all groups reduce yielding ability, but with different intensity. This question is quite significant, but there is a small number of researches in this direction.

Question № 4: What are the ways of the broomrape dispersion and methods of preventing its spreading?

The director of the company "Eurosem" said that according to world studies, the main reason for the rapid spread of the broomrape is human activity:

“The dispersion occurs by the working with tillage equipment and harvesters. The seeds are transferred by the wheels of equipment over long distances. The main guarantee of the control of the broomrape spreading is sanitary treatment of equipment. In order to avoid the spreading of the broomrape, it is necessary to wash the wheels, especially if the equipment is rented.”

On the condition that this problem already exists on the fields of the enterprise, a plan of actions should be developed, according to which all operations should be carried out firstly on clean fields, and only then on fields, which are affected by the broomrape.

In addition to the technology, the broomrape is able to cross over to the sunflower from other cultures. Therefore, even if there is no sunflower on the field, but there are wormwood or weed cannabis, on which it also develops well, there is a risk of the spreading of this problem. It is necessary to conduct monitoring and extirpate weeds in and around the field.

It is very important to sow certified seeds. The seeds of the sunflower broomrape are electrostatic. This means that after opening the box, seeds stick to the soil or are carried by the wind at short distance. However, there is a slight chance of basket damage. This problem can be avoided with the purchase of original certified seeds.

Question №5: Do culture-provocateurs such as maize and sorghum help by the abatement with the broomrape?

Hereupon this issue Dmytryi Shatsman said the following:

“Unfortunately, such researches are not conducted in Ukraine. There is information on the basis of Russian studies that were conducted in 2012. According to the data, not all maize hybrids equally provoke the broomrape seed sprouting. Therefore, there is no saying that maize crops will be able to deal with this issue. Sorghum is also not a panacea. In addition, the sowing of these crops is carried out in a wide-row method, and the seeds of the broomrape appear from a distance of 5-10 mm. Thus, all the seeds remain in the space between rows. The cultures such as bird rape, mustard, rape, soybean do not at all provoke the sprouting of the broomrape seeds. ”

Question №6: What are the most effective methods of abatement with the broomrape?

1. The most famous method of abatement with the broomrape is Clearfield technology, which allows to control the population of the broomrape.

2. Autumn broadcast sowing of sunflower with the use of green fallow. Provocative sowing stimulates the sprouting of the broomrape, after which the sowing is extirpated.

3. According to some reports, No-till technology is able to control the problem, which is partially concerned the broomrape. If to talk about tilling, then it’s more like conservation of the seeds of the parasitic plant and protecting it from unfavorable weather conditions.

Unfortunately, today there is no universal panacea against the sunflower broomrape. But observation of the before-mentioned recommendations will delay its development and dispersion.