Lobesia botrana in table grapes, blueberries, plums and ... analysis and experience of the industry and projections for the 2015-2016 season

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Carlos Barriga highlights the importance for the industry of maintaining a low population of Lobesia botrana and hopefully eradicate the plague because among the main markets to which the Chilean fruit comes are, for example, the US, Mexico and Canada. Markets that represent 47% of exports of table grapes, 56% of cranberry and 35% of exports of plums from our country.

While Lobesia botrana o Vine cluster moth (LB), is present in near 50 Countries: 27 of Europe, 15 of Asia, 6 of Africa and 3 of America; in important markets it is considered as not present, in the process of eradication (USA) or directly as a quarantine pest.

Within the countries where the plague is not present, there are also some giants from the Far East, markets that concentrate more and more weight in several fruit species. For example, the participation of these countries in table grapes, cranberries and plums is very important (22,10%, 16.30% and 21,70% respectively) and they are also markets that are growing in importance. Worse still, because the fruit trees mentioned above must also be added to the cherry (close to 80% goes to China). All these fruit trees run the risk of undergoing new regulations or having to fumigate the fruit, which implies a significant increase in costs and also has negative effects on the condition of the product.

Situation of the plague season 2014 - 2015

The official data on catches in pheromone traps, surface, number of farms, prospections and larvae are indicators that allow to measure the presence and evolution of the pest. This is a dynamic pest and as we increase the area under sexual confusion we will have to change indicators because this technique cancels the catches in pheromone traps so we will have to incorporate other indicators to know the success or failure of the program and not just the number of males that fall into the traps. I think that an indicator that will have to be very important in the future is that of larva fruit. It is a very useful indicator for fruit growing because a fruit with an immature state, be it egg or larva, leaves that fruit out of the markets.

The figures show a strong increase in the populations of LB, but according to Barriga, when analyzing them, we must consider that the program faced important technical and budgetary limitations last season.   

The 1 table shows the total of catches for each of the three flights of last season, the number of orchards affected and the vines segmented into table grapes, for wine and mixed. "The important thing about these figures are the 450.000 moths that were captured on the third flight as it tells us what the first flight of this season might be like. It's a huge amount and it's a bigger number than all the moths caught the previous season. ", warns the specialist.

Although the program achieved some success by containing and preventing new plant species from being added to the control, "We are not happy with these numbers"says Barriga. But he affirms that the figures serve as a guideline to make the necessary adjustments in order to lower the population of this species of moth in the country.

The 2 table shows that the regions where the pest is in containment take a very high percentage of the catch (99,8% of total catches). About the 99% in the case of table grapes was captured in those three regions, but especially in the one of O'Higgins and Maule, where the greatest number of catches occurs in vines. Likewise, the largest amount of catches in cranberry occurs in the Maule but in the case of plums the largest number is in the region of O'Higgins. According to the figures of the SAG, the adult catches in wine grapes represent the 88,1% and the table grape 7,5%, the 99,8% of adult catches are concentrated in the regions in contention, between which O'Higgins and Maule present the 94,5%. Also according to the SAG, in the regions in eradication the good results have been maintained since they represent only the 0,11% of the total catches.

Table2

Catches in bibliographic hosts and urban areas

In the data of catches in bibliographic hosts (non-vine, blueberry or plum), apples and pears have 33.800 captures; nectarines, peaches and apricots 34.600 captures; kiwi 10.690 catches, etc. But among the bibliographic hosts, the large number of catches in cherry orchards stands out: 64.000 catches. "The cherry tree is a fruit tree in which by the end of December is almost all the harvested fruit, despite which, the catches exceed the 64.000 individuals. This is a number greater than the number of catches in cranberry and plum, "warns Barriga. 

Based on these figures, the specialist calls for the industry not only to maintain the control measures, but also to apply the necessary filters and reinforce the phytosanitary programs to avoid having an accident that could complicate, for example, the cherry market .

Much of these catches in the aforementioned bibliographic hosts, to which olive trees and pomegranates are added, are due to the fact that these fruit trees are located in the vicinity of grape orchards but, according to the expert, there is a danger that the moth could end up feeding of one of these fruit trees.

In the case of urban areas, more than 374.000 moths were captured, 43% of them in O'Higgins and another 51% in Maule. So the total number of captures, adding all the categories, is 1.375.836 moths.

Table3

Prospecting of immature states: a key fact

According to Carlos Barriga, the number of immature states found in the surveys is a very important fact. In the 3 table, with data recorded up to the March 30, the number of orchards surveyed and the regions where the immature states were found are shown. "In wine grapes, an amount close to 30% of the surveys were positive while only 18% in table grapes, despite the fact that in the latter almost 100% of the orchards were surveyed because this is a mandatory action to access various markets. Thus, the presence of a single larva or egg is enough to stay out of several markets." 

In the case of cherry tree, it is observed that there were two detections of immature stages, both in the Maule Region. "Fortunately, they were able to discover it on time and it did not become bigger," says the expert, despite the notices that the SAG had to send to the markets "

Another indicator that worries Barriga is the evolution of the area under compulsory control. "Of 72.400 has of vines of the year 2012-13 we pass to 92.685 has of vines the year 2014-15, to which adds 4.639 has of blueberry and 15.156 has of plum, completing 112.475 has totals. Considering that the surface of fruit trees and vines in Chile is close to the 400.000 has, we are approaching that the 50% of the area planted with fruit trees and vines in the country is under compulsory control, "he says. That is, the 50% of the near 180.000 has vines (for wine and table), the 30% of the surface of blueberries and almost an 85% of the area planted with plum under mandatory control.

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Projections: how to change the trend and achieve containment, suppression and eradication

However, despite the obligatory control carried out last season on cranberries and vines last season, larvae were found in the fruit, which for the professional is indicative that the necessary adjustments must be made in order to improve control. 

As you can see in the graphic and in the table that accompanies it, for the 2015-16 season, a trap is projected in 1.100.000 traps. Lobesia botrana while for the 2016-17 season the projection is that the traps will capture about 1.600.000 male grapevine moths. For this, "We need to do more of what we were doing but also to do better", says Barriga.

"These results have led us to think that we should make real and effective changes in chemical treatments but also make the maximum effort to achieve the largest surface treated with emitters of sexual confusion (ECS). The chemical treatments, mainly the opportunity of the treatments require of greater precision since obviously a single notice of flight that involves three regions is of much less precision than eight warnings for those same three regions (as it will be this season). This year, using the monitoring stations, the temperature projections and the capture data, we will achieve greater precision in chemical applications. Today, chemical control is the basis of our control strategy "says the professional.

Likewise, Barriga affirms that the area covered by ECS must be increased and also the criteria used to distribute them in the different regions must be homogenized, since, as he explains, last year different criteria were used from one region to another. "We believe that by working these two aspects we will achieve better results"He says.

For proper management of an official control pest, legal control is very important. According to the professional, this factor is present in Chile in very good shape and is expressed in national and regional resolutions, control strategy and enforcement actions and internal quarantine. "As already said, it is necessary to specify much better the applications of phytosanitary products to the crop according to the programs suggested by Asoex for each species and to maintain a period of adequate protection. In previous years it mattered more the number of applications but now that concept was changed to the period in which the crop should be protected, especially the fruit, to prevent the moth from entering.He says.

"I think that today we are working well on the selection of products, so from the list of 11 accepted products, 7 were eliminated and the protection period of some products was reduced, which will affect the number of applications per every generation” (it should be applied more times). All information on authorized pesticides, regulations, strategies, procedures, etc. can be consulted on the SAG website (www.sag.cl).

Within what Barriga calls biotechnical control are tools such as diffusers of sexual confusion and sprayable pheromone, but also the professional points out the technique of the sterile insect, which, according to Barriga, would represent a breakthrough, "Because it is the way to control the plague in urban areas and likewise it would be of great help in the productive areas".

Another form of control, "somewhat forgotten," he says, is cultural control. "It can be very helpful to manage and eliminate weeds, especially bindweeds, since the literature defines that good weed control in the orchard and its surroundings can be very effective. Normally there are plants, even vines, in the surroundings of the orchard on which no actions are carried out. Perhaps does not happen to make chemical applications but to place confusers and eliminate inflorescences and clusters since normally in suburban areas these elements do not become edible fruit as it rots on the road by action of the same LB, botrytis, etc. ".

In Chile the potential of biological control is being studied since in Europe this plague has many natural enemies and in Chile they are still not well known. "The first studies are being carried out that could be very helpful in urban areas", according to Barriga.

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Strategy and methods of control with emitters of sexual confusion

The control technique using ECS ​​has some limitations that Barriga considers important to review in order not to make mistakes in the handling of the moth.

The specialist explains that this is a technique that acts when it is implemented in large areas and that the larger the treated area, the greater the efficiency. That is, it is not efficient -for example- in individual gardens. On the other hand, it makes it difficult to follow the pest through pheromone traps (since there are no catches) and the diffusers do not completely cover the period of three generations of the pest, so control must be reinforced either with chemical applications or aspermable pheromone. The risk of reinfestation should be borne in mind by gravid females flying from neighboring areas (edge ​​effect) and that their effectiveness decreases in high-population areas since casual encounters between females and males increase. It also increases the risk of suffering other pests as it is a specific pheromone for LB and because no chemicals are applied (for example, eulias and proeulias). Its action is cumulative so it achieves effect when used for a period of 4 or 5 years. Finally, its effectiveness is affected by climatic factors such as wind, irradiation and temperature, and by topography, architecture and orchard orientation.

The 4 table shows the percentage of area treated by region with ECS. "In the MRI, where both the number of catches and the percentage of larvae decreased, we found two important factors, covered an 24% of the surface with this technique and it was also very well located. In the regions of O'Higgins and Maule, meanwhile, the 2014-15 season was only covered by 16 and 17% respectively. This year those percentages will go up to an 35% in O'Higgins and up to 61% in the Maule area treated with issuers. This plus chemical controls should give very good results ", Señala. 

How to modify the current trend  de  the plague

For the professional it is necessary to design a national medium and long-term program to count on time with the necessary inputs and to be able to give consistency to the strategy to achieve the short, medium and long-term goals. "We must increase the area treated with ECS, from 50 thousand ha budgeted by the SAG for 2016 to at least 110 thousand ha", he points out. What he estimates represents an additional cost close to US $ 7.8 million, only to deal with productive areas. 

As already indicated, it suggests increasing the effectiveness of chemical controls by improving the accuracy of the application dates of the products considering their periods of protection. The technique of sexual confusion, considering a maximum duration of the emitters of 150 days, must be complemented with chemical applications. The surveillance and especially the control of the SAG should be focused on the producers with the highest catches (CTD: catch / trap / day, highest) in each region and commune.

In addition, it considers important, at the level of urban control, to soon increase the area treated with issuers, especially Maule and O'Higgins. "Treat the urban areas of these regions and some municipalities of the RM, would represent an additional cost close to US $ 2,5 million", esteem.

It recommends focusing the resources of INDAP on the installation of ECS and not on the payment of chemical applications. "As an industry we must promote adjustments in the phytosanitary programs of other species, such as pits, in order to reduce the risk of finding fruits with immature stages of the pest. In that sense we must continue with the program of private control for cherries and filter actions at the level of packing plants to avoid the risk of appearing larvae fruit or diminishing the risk to the minimum ", the agronomist points out.

Finally, he assures that the results of research in the sterile insect technique (SIT) should be accelerated, especially for the treatment of urban areas and invest in the training of professional and technical personnel in charge of pest and disease control in the gardens. "Because if there is a deficit in the producers it is the real ignorance of the plague, which probably has its origin in that the control of the plague was in the hands of the State. But nowadays the control of Lobesia botrana is mainly a matter of the producers, the main ones interested in defending their fruit from the plague ", Carlos Barriga. 

Evolution of catches of Lobese botrana in California

Table4

Control in production areas: ECS Napa county plus phytosanitary applications. Other counties only product applications in 1ª, 2ª and 3ª generation.

Control in urban areas: Elimination of floral primordia and bunches. Application of Bacillus. In some cases use of ECS.

The table shows the counties in California that have had problems since the 2019 year onwards. The main affected county was Napa, where catches of males were reached on 100.000, while the other counties show very small numbers of catches.

Today the real situation in California (2014) is that Napa had no catches and that there are 7 counties that are free of the plague. The luck of the Americans is that they discovered the presence of the plague at a very good time and activated their program very early.

Sexual confusion, as a control technique, in California was used only in Napa County, whose surface is used mainly for the production of wine grapes. This control technique was combined with the application of phytosanitary products. In the rest of the counties the good result was achieved only through the application of agrochemicals.

Another fortunate condition for them is that the control areas are fairly clean, there are no hamlets or houses between the fields, and few houses have vines. In cases where the houses had vines these were removed the inflorescences or clusters or applied Bacillus tunigencis

This shows that the near elimination of the population of Lobesia. It is certainly not eradicated from the US since a capture still persists but we believe that eradication will be achieved in two years' time because at least 5 generations have to pass to achieve eradication.

Strategy and methods of control with phytosanitary products

The chemical products are going to be the base of the control this season and in the first place Barriga advises to realize extra applications to reinforce the borders of the quarters. 

Limitations of the control with phytosanitary products or errors in the application:

• Definition of the application date.

• Product not suitable for the time of application.

• Bad coverage in the application, bunches or fruit covered by the foliage.

• Bad or wrong distribution of the applied solution.

• There is a risk of generating resistance to conventional phytosanitary products.

• Due to the protection period, the risk of waste increases (MRL).

• Increase in the number of metabolites or number of residues in the fruit.

• Negative impact on the environment.

• When the treatments have no effect or do not control the entire population, the insects that survive are able to take the infestation to high levels again.

Source: Redagrícola

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