How to treat vine diseases? 5 things you need to know

Among the major threats faced by the winemaker in managing his or her land, vine diseases are certainly the most relevant.

On the other hand, vine wood diseases that are not prevented and not promptly addressed can lead to serious damage to the health of the plant and, in some cases, result in its death.

But how to treat grape diseases?

In this guide, we wanted to share with all our readers 5 things that are good to know to ensure your vine has greater longevity and higher quality production.

Prevention is the most effective weapon

As is well known, prevention is the most effective weapon against vine diseases. Indeed, a properly managed vineyard is more resistant to pathogen attacks and, even when they occur, is better able to fight them off.

That is why the first step can only be represented bythe adoption of the most correct agronomic practices starting with the choice of the planting site, opting for a well-drained soil, with the right exposure to the sun and good air circulation. Planting density and training system must also be chosen carefully: it is best to focus on solutions that ensure good ventilation between the rows and within the canopy, to be accompanied by balanced pruning that avoids both excessive vigor and weakening of the plant.

Then as far as soil management is concerned, let us recall how controlled grassing and the use of green manure can increase the biodiversity of the vineyard, thus promoting the presence of beneficial insects and beneficial microorganisms that naturally fight pathogens. When it becomes necessary, irrigation should be managed with specific care, avoiding excesses that could promote disease development.

Finally, the importance of using certified propagation material should not be underestimated. In fact, let us remember that many vine diseases, and in particular those of a viral nature, are transmitted through rooted cuttings: therefore, it becomes essential to make sure that these come from authorized nurseries and that they have undergone the health checks required by the regulations.

Early intervention on vine wood diseases

If the preventive phase has failed to avert vine health hazards, it is, of course, important to intervene proactively and act promptly as soon as abnormal signs occur. Neglected vine wood diseases can in fact result in serious harm to the plant, even leading to its premature death.

For example, among the most widespread and feared vine wood diseases is esca disease, the vine canker, which begins with yellow or reddish streaks on the leaves and desiccation, eventually leading to wilting of the plant.

Unfortunately, the diagnosis of these diseases is not straightforward. In fact, the symptoms can be easily confused–by less experienced eyes–with those of other diseases or abiotic stresses.

This is also why in many cases people come to deal with the disease late, or incorrectly. And, to make matters worse, there is the fact that there are no really effective methods to combat the disease once it is established in wood.

For this very reason, the main activities focus precisely on prevention, with special attention to pruning operations-the time when trauma and wounds are created that are potential entry routes for pathogens.

To contain the risks, it is therefore good:

• Carry out pruning on dry and preferably cold days
• Disinfect cutting tools between plants
• Protect pruning wounds with appropriate mastics or copper products
• Remove and burn infected pruning material
• consider applying products containing Trichoderma, an antagonistic fungus that can help protect wounds.

In more severe cases, when the infection is advanced, it may instead be necessary to resort to cutting down the plant or, in even more extreme cases, to its complete explantation. Unfortunately, even such extreme measures cannot always be considered decisive.

Acting in an integrated way

A third course of action to combat grape diseases is to proceed in an integrated manner.

Unfortunately, in fact, plants can be affected simultaneously by several diseases, such as those directly affecting the clusters, botrytis or gray mold (Botrytis cinerea), downy mild ew (Plasmopara viticola).

In particular, botrytis is mainly manifested by grayish rot on the bunches, especially in wet and rainy years. Downy mildew, on the other hand, can cause complete bunch desiccation or, in late infections, the characteristic “spot rot.”

Well, to effectively combat these and other grape diseases, the most modern and ecologically sustainable approach is that of integrated action, a strategy that combines different control techniques, limiting the use of chemicals to only those cases of actual need and favoring methods with a low environmental impact.

Let us try to summarize in this table what the main lines of integrated action are:

Anticipating disease development with climate analysis

Additional course of action that the farmer should consider in his vine disease prevention strategy is to understand that climate plays a crucial role in the development of various plant diseases.

Factors such as temperature, humidity, precipitation and windiness are conditions that may or may not favorably influence the biological cycle of pathogens and the susceptibility of the plant to attack.

Here, then, is where understanding how these dynamics operate can help anticipate disease development and intervene preventively, before infection spreads in the vineyard.

We have briefly summarized the impact of some of the major climate elements in this table.

In good evidence, knowing about these interactions can be useful in feeding forecasting models that-combining real-time weather data with pathogen biology and vine phenology-can predict which periods of greatest risk for major diseases and, consequently, set up better counter strategies.

Use more disease-resistant grape varieties

Another landmark approach for viticulture is the use of grape varieties that are resistant or tolerant to major grape diseases. These are grape varieties developed through genetic improvement programs, which can incorporate resistance genes from species that are more resistant to pathogens such as downy mildew and powdery mildew.

Their choice and adoption allows for some important benefits such as, among the main ones, a reduction in the number of phytosanitary treatments required during the growing season. In many cases, for example, we go from the 10-15 annual treatments required by traditional vines to only 2-3 interventions.

Consider also how the enological quality of the most disease-resistant grape varieties is constantly improving. The result is that-although the subject generates positions that are sometimes not very conciliatory-many of them are already capable of producing wines of an excellent level, quite comparable to those that can be obtained through traditional varieties.

To complete the topic, however, it should be emphasized that the resistance of these grape varieties is not meant to be absolute and permanent. Instead, it is more correct to define their tolerance as high but not definitive, with the consequence that most attacks, if one is not under strong pathogen pressure, can be overcome with less burden.

Also in light of these reflections, in the case of choosing resistant vines, it is always advisable to maintain adequate health surveillance of the vineyard, still apply good preventive agronomic practices, and carry out treatments during periods of higher risk or when environmental conditions are particularly favorable for disease development.

Therefore, we can only remind, in conclusion, how the most effective management of vine diseases requires an integrated and organic approach, whose goal is not necessarily to completely eliminate pathogens from the vineyard, but rather to keep diseases below the threshold of economic damage, while preserving the balance of the agroecosystem.

An approach that can ensure abundant and quality production, actively contributing to the long-term sustainability of viticulture.