The warm months are characterised by increased pest and disease pressure. The vine undergoes key developmental stages during this critical period, including flowering, fruit set, and berry ripening. Proper pest and disease management during summer is essential for achieving optimal grape quality and yield.
Identification of Common Pests and Diseases
Effective pest and disease management in viticulture begins with a thorough understanding of the common grapevine threats. Accurate identification of these threats facilitates the application of integrated pest management (IPM) strategies, ensuring a proactive and sustainable approach to safeguarding grape crops. Refer to the characteristics of grapevine pests and diseases covered in previous units.
Integrated Pest Management Strategies
Implementing preventative measures against pests and diseases in a vineyard during summertime requires the integration of biological and cultural control methods. By integrating these practices into their vineyard management plans, grape growers can enhance the resilience of their vineyards while minimising the reliance on chemical interventions. Regular education and adaptation to the specific conditions of the region are crucial for successful implementation.
A. Biological control
Biological control methods harness natural predators and organisms to manage pests in the vineyard, offering sustainable and environmentally friendly alternatives for grape growers.
Introducing beneficial insects is a key aspect of biological control. Predatory insects such as ladybugs, lacewings, and parasitic wasps can help regulate pest populations by preying on common vineyard pests like aphids and mites. Additionally, encouraging the presence of spiders in the vineyard serves as a natural control measure against various pests.
Nematodes, microscopic soil-dwelling organisms, can also be employed for biological control. Certain species of entomopathogenic nematodes are effective in targeting soil-dwelling pests, including larvae of grapevine pests. Integrating these beneficial organisms into the vineyard ecosystem promotes a balanced and sustainable approach to pest management. Grape growers need to understand the specific needs and lifecycles of these beneficial organisms to maximise their effectiveness in controlling pests.
B. Cultural Control Methods
Cultural control methods focus on altering vineyard practices to create an environment that is less susceptible to pest development. Regular monitoring of the vineyard for signs of pests and diseases is a fundamental cultural practice, allowing growers to intervene promptly when necessary.
Vine spacing:
By providing adequate spacing, increased airflow and sunlight penetration reduce humidity levels, creating an environment less favourable for fungal diseases, such as powdery mildew and downy mildew. Proper spacing also facilitates easier monitoring and management of pests.
Cover Cropping for Pest Suppression:
Cover cropping is the strategic planting of specific vegetation between vine rows. Certain cover crops attract beneficial insects, creating a habitat that supports natural enemies of pests. Additionally, cover crops contribute to soil health, nutrient cycling, and weed suppression, enhancing overall vineyard resilience.
Choosing suitable cover crops for pest and disease control in a vineyard requires careful consideration of the region’s mesoclimate, soil conditions, and prevalent pests and diseases. Cereals and legumes are often used as cover crops, but several options can contribute to these goals.
- Marigold (Tagetes) is known for its pest-repelling properties. It releases natural compounds that deter nematodes and attracts beneficial insects.
- Mustard (Brassica) exhibits bio fumigation properties, suppressing soilborne pests and pathogens, while also contributing to nutrient cycling and weed suppression.
- Buckwheat (Fagopyrum esculentum), a quick-growing cover crop, attracts beneficial insects like predatory wasps and contributes to allelopathic weed suppression. Allelopathy is where a plant releases chemicals in the soil which make it difficult for other plants to grow with it.
- Clover (Trifolium), especially white clover, aids in nitrogen fixation, improves soil fertility, and acts as a living mulch for weed suppression.
- Sunflowers (Helianthus annuus) attract beneficial insects and provide habitat for spiders, acting as natural predators of various pests.
- Sorghum Sudan Grass (Sorghum bicolour x Sorghum sudanense) is a fast-growing grass cover crop effective for weed suppression and allelopathic control.
- Phacelia (Phacelia tanacetifolia) attracts pollinators and beneficial insects, contributing to biodiversity and supporting natural pest control.
Cereal cover crops planted between vine rows
However, the effectiveness of these cover crops may vary depending on specific vineyard conditions. It is essential to integrate cover crops into a comprehensive vineyard management plan, combining them with other practices for an integrated approach to pest and disease control.
Sanitation Measures:
Proper sanitation practices, such as the timely removal and disposal of pruned vine material, should also be included in IPM. Removing potential habitats for pests reduces the risk of infestations and diseases.
Other Aspects of Cultural Control:
- Selecting disease-resistant rootstocks can enhance the overall resilience of the vineyard.
- Maintain well-ventilated canopies to reduce humidity and minimise conditions which favour fungal diseases.
- Thin grape clusters to achieve optimal spacing, reducing the risk of diseases like Botrytis cinerea in compact grape clusters.
- Avoid over-irrigation, as excess moisture can contribute to the development of certain diseases.
- Train vineyard staff on pest and disease identification and management practices.
C. Chemical Control
Chemical control methods involve the targeted use of pesticides to manage pests in the vineyard. Grape growers can employ these methods as part of an integrated pest management strategy. Follow all label precautions and directions, including requirements for protective equipment.
Selective Pesticide Application:
Selective pesticides specifically target certain pests while minimising impact on non-target organisms and the environment. For instance, selective pesticides can effectively control grapevine pests such as grape moths and leafhoppers while preserving beneficial insects that contribute to natural pest control. Careful consideration of the pesticide’s mode of action and its compatibility with the vineyard ecosystem is essential to ensure effective and sustainable pest management.
Targeted Timing of Pesticide Application:
The timing of pesticide application is a critical factor in maximising effectiveness while minimising environmental impact. Grape growers should align pesticide application with the lifecycle of the target pests. For example, applying pesticides during the initial stages of pest development can prevent population build-up. Additionally, considering factors such as weather conditions and the phenological stage of the grapevines ensures optimal efficacy. Timely and targeted pesticide use not only enhances control but also minimises the quantity of chemicals needed, promoting sustainable vineyard practices.
Alternatives to Conventional Chemicals:
Grape growers are encouraged to explore alternatives to conventional chemicals, embracing sustainable and eco-friendly options.
Biopesticides are a type of pesticide derived from natural sources such as animals, plants, bacteria, and certain minerals. They can be classified into three main types:
- Biochemical pesticides are substances found in nature that control pests through non-toxic mechanisms. Examples include sex pheromones, which disrupt pest mating, and plant extracts that lure pests into traps.
- Microbial pesticides refer to pesticides whose active ingredient is a microorganism, like a bacterium, fungus, virus, or protozoan.
- Plant-incorporated-protectants (PIPs) are pesticidal substances produced by plants that have been genetically altered to include specific pest-resistant traits.
Integrating these alternative methods reduces reliance on synthetic chemicals and contributes to the long-term health and sustainability of the vineyard ecosystem.
D. Monitoring and Thresholds
Monitoring pest populations:
Monitoring in a vineyard involves regular and systematic observation of grapevines to detect the presence and assess the levels of pest and disease activity.
Visual inspection is the most common monitoring technique. It involves walking through the vineyard and visually inspecting vines for signs of pests and diseases, such as insect damage, fungal spots, or unusual vine growth. Therefore, vineyard workers must be adequately trained to identify signs of pests and diseases. Pay attention to low-lying areas or where water tends to accumulate. These are usually problem areas for weed growth.
Environmental monitoring should be included in IPM practices. Keeping track of weather conditions, as certain pests and diseases thrive under specific environmental conditions.
Traps and monitoring devices, such as pheromone traps for insects, sticky traps, or other monitoring devices, can be used to detect and measure the population levels of certain pests.
Pheromone trap in a vineyard
Records of inspection and monitoring must be kept for tracking of pest and weed populations from year to year to better understand ongoing pest and disease issues. Also maintain detailed records of pest and disease occurrences, treatments applied, and their effectiveness. Historical data can be used to refine and improve future preventative measures.
Thresholds:
Thresholds in pest and disease management refer to the level of pest or disease presence at which control measures should be taken to prevent considerable damage to the vines or fruit. These thresholds are essential for making economically and environmentally sound decisions.
An economic threshold is the point at which the cost of damage by pests or diseases equals the cost of control measures. If pest or disease levels are below this threshold, the cost of treatment may not be justified. Action thresholds are set lower than economic thresholds. These are the levels at which action should be taken to prevent the pest or disease population from reaching economically damaging levels.
For diseases, thresholds can be based on disease forecasting models that predict disease risk based on environmental conditions like humidity and temperature.