The Chilean phytopathologist Andrés France Iglesias is characterized by disclosing the need for a cultural change in producers, warning that there are diseases that can end an orchard if advance measures are not taken. "The secret lies in prevention," says the researcher from the Agricultural Research Institute (INIA).

"Today the most important diseases are clearly identified and most producers know how to recognize them. The problem seems to be that it is difficult to prevent," he says. He emphasizes that when the orchard remains in the same soil for several years, diseases establish themselves and increase their incidence over time, for this reason it is essential to prevent and not wait for the orchard to be sick to act.

The green part...

Andrés France insists that measures must be taken in advance, especially in a type of berry such as the blueberry, which suffers from more diseases than the average berry. In the case of pathogens that affect the aerial part of the blueberry plant, especially its foliage, it is very difficult for them to kill an orchard, but they can cause disasters by leaving the crop in very weakened conditions, since they affect the entire green part , such as new leaves, petioles, peduncles, shoots and stems. Its main symptoms appear as pustules, or small bulges with necrotic characteristics that reduce the leaf area and thus also reduce the possibilities of photosynthesis of the plant.

In Trujillo

In his numerous investigations, the INIA plant pathologist and researcher, Andrés France, who will be one of the speakers at the Trujillo International Blueberry Seminar next July, has made a detailed study and analysis of the main conditions that affect blueberries in Peru and that he will share in his presentation, “Blueberry foliar diseases: a growing challenge”.

“In general, they are diseases that weaken the plant and affect the production and quality of the fruit. They are relatively easy to identify because they are visible through the sheet. Its control is achieved with contact and systemic products. They are also easy to confuse with some abiotic stress: frost, damage from fertilizers or agrochemicals”, explains Andrés France.

rust and powdery mildew

Regarding rust (Naohidemyces vaccinii), which is a disease that spreads very easily in Peru, it can be said that the pustules appear on the underside of the leaf and are yellow in color, due to the accumulation of spores. It is very aggressive and spreads easily through wind and contaminated waste. Leaf necrosis occurs and it self-defoliates, as a defense mechanism, so that the plague does not continue to advance. This loss of leaves causes a decrease in the vigor of the plant, which ages faster, affecting its production and yield, and thus also the quality of the fruit.

Similar to rust is powdery mildew (Microsphaera vaccinii), which has a higher incidence in Peru. “In theory, it is very easy to control because the entire structure of the fungus is on the surface of the leaf. Only 5% of the living part is inserted in the epidermal cells, which is where it feeds. But if the problem is very intense, this set of conidia repels water, therefore, also the product that we are applying”, he assures.

"You don't have to go to those extremes to control, otherwise it will be very difficult," warns the expert and insists that it is important to carry out an early control, because powdery mildew has an explosive appearance and it takes 2 or 3 days from the first symptoms until the plant looks very damaged, not 20 days, as is the case with rust. “In addition, it is very easy to spread through the wind. Produces large amounts of spores and russet leaves, affecting leaf area, photosynthesis, and carbohydrate accumulation. The fruit decreases in quantity and quality. It is a short-cycle pathogen that requires recurring applications”, he explains in detail.

Both Rust and Powdery Mildew are managed together, preventing the entry of the disease into the orchard through quarantine of new plants. The plant pathologist even recommends restricting the movement of personnel from diseased places to healthy places.

Botrytis and Alternaria

In the case of necrotic pustules, caused by Alternaria sp., of special incidence in Peru, they can be easily confused with those produced by chemical products applied in areas with high temperatures. The main characteristic is that the spots caused by Alternaria have well-defined borders delimited by a purple color. Reproductive structures occur in the center of the lesion. "Depending on the varieties, the spots can be quite large and, at that level of damage, the plant self-sheds leaves as a defense mechanism," says France.

On the other hand, in addition to Alternaria, the crop is attacked by Botrytis, gray mold or Botrytis cinerea, also known as gray rot, both in its endogenous and exogenous version. Botrytis is an endoparasitic fungus whose spores take advantage of any wound or small fissure in the plant to penetrate inside. If the right conditions are given, such as mild temperatures between 15º C and 25º C and high humidity, these spores can germinate inside, causing rotting or necrosis of the infected tissues.

It is a very frequent disease, which can cause, in the first instance, the appearance of spots on flowers and fruits and, if the infection continues, they end up deforming and rotting. In those cases, the losses for farmers are substantial.

Cultural change

The scientist's message is to prevent and generate an important cultural change in this field. Do not continue reacting when the disease appeared. “Fruit growing is not an annual crop. There is an important investment and that must be protected”, he warns.

The talk, scheduled for the first day of the International Blueberry Seminar on July 6 and 7, “Blueberry foliar diseases: a growing challenge”, will deal in detail with these and other pathogens that affect the blueberry crop, addressing their behavior, their symptoms, their level of impact and their treatment, because it is a vital issue for the efficient development of crops and a determining factor for the results of productivity and fruit quality.

Extensive Program

The meeting will be held at the Hotel Costa del Sol Windham Trujillo Golf, and together with the agronomist and international consultant Andrés France, important speakers will participate, such as Bruno Defillipi, Juan Hirzel, Juan Francisco Palma, María del Carmen Salas, Martín Cotos, David León , Emilio Merino, Eduardo Donoso, Antonio Gaete, Paula del Valle, Claudio Yáñez, Edgar de la Cruz Huertas and Claudio Moreno, addressing nutrition issues in their different aspects, fertigation, post-harvest, biological control of diseases, organic production, new applications, quality and arrival, among many other issues. Beginning with the exhibition "Past, present and future of the blueberry business in Peru", by Federico Beltrán, manager of Terra Business SAC.