Hail damage and your apple orchard

Hail damage can occur at any time during the fruit-growing season. Usually, when hail occurs early in the season, it causes deep depressions and deforms the fruit, while later-season hail damage often bruises the fruit. Hailstone size and intensity will also influence how much damage the fruit receives.

Assessing the damage

Assessing the damage to an orchard after a hailstorm helps you make informed economic decisions for the rest of the growing season. Block-by-block assessments should be carried out to determine whether it is economical to proceed with normal crop management for the current season or not.

Assessing the damage can be as simple as recording how many fruit are damaged from a sample of 100, providing an estimation of the percentage of fruit affected. If the damage intensity varies significantly in a block, count multiple samples of 100 fruit to improve accuracy. Without assessment data, it will be difficult to make confident and informed decisions on how to proceed with management, storage and processing.

Disease risk

Hail damage predisposes trees and fruit to infection from pests and diseases, so careful management after hail is crucial. Severely damaged stems and branches should be pruned (if practical), and fallen fruit should be cleared from the orchard to reduce infection sources.

Fruit rot and associated decay are more prevalent after a hailstorm, especially where high relative humidity combines with fruit and tree damage to encourage disease development. Applying fungicide immediately after hail decreases the risk of diseases establishing in small puncture wounds in the fruit. Large wounds can occur if branches are snapped; these can be covered with a water-based paint to avoid desiccation and decrease infection risk. Experience shows that hail-damaged fruit is more likely to break down in storage due to fungal rot infections.

Reducing the effect of hail damage

Tree health inputs such as fertiliser and water should be maintained, even in severely damaged blocks. Allowing the trees to suffer additional stress from a lack of nutrition or water will affect next year’s buds and crops.

Trees that were damaged early in the season might benefit from a layer of mulch around their bases. Mulch can decrease soil temperature fluctuations by acting as a buffer, which is particularly useful in the summer months. Mulch also helps retain water in the root zone, decreasing water stress in the tree.

Thinning can be used to selectively remove hail-damaged fruit and to improve the yield and quality of remaining fruit. Deciding to undertake additional thinning should be guided by your damage assessments, as well as considering how additional thinning could affect final fruit size. Removing damaged fruit early, if practical, can improve the final yield.

If growers choose to leave the fruit on the trees and manage it through to harvest, it is important that this fruit is not left to become over-mature because this will make it more susceptible to breakdown in storage.

After harvest

Applying a postharvest fungicide dip to the fruit before it goes into storage can reduce the risk of fungal infections occurring. Do not use treatments where fruit is being exported unless they are permitted by the importing country.

Long-term storage of hail-damaged fruit is not a reliable strategy. Significant losses due to fruit breakdown are highly likely. Fruit with the most severe damage should be processed first and stored for the shortest period.

Some growers might choose not to treat their hail-damaged fruit due to extra costs. In these cases, it is important to remember that ethylene levels will increase in the storage room after harvest. This will accelerate the breakdown and reduce the time the fruit can be stored.

For more information on postharvest fungicides, refer to the Orchard plant protection guide.

Marketing

Hail damage will reduce the market value of the fruit, and after hailstorms, the local juice market is often saturated with produce, resulting in lower prices. Therefore, different marketing options might provide more beneficial ways to sell fruit.

Local markets can present opportunities for growers to reach out to the local community. This can also ‘close the gap’ between consumer perception and what really occurs in an orchard. Creating awareness around these problems in orchards can gain significant consumer understanding and support.

‘Pick your own’ can be another option for smaller growers. It involves allowing consumers to enter your farm to pick the fruit straight from the orchard. Although this can be a great way to get community involvement in your orchard, visitors can unintentionally bring pests, diseases and weed seeds with them, posing a biosecurity risk to your orchard. There are simple ways to reduce this risk when planning to invite the public into your orchard, including:

• providing a designated parking area away from production areas and packing houses
• having an area for visitors to wash their hands and providing footbaths for them to clean their shoes before entering the blocks
• if practical, have dedicated areas where pick your own can occur, instead of opening the whole orchard to the public
• check the areas visited by customers often for signs of diseases, pests and weeds.

Hail-damaged fruit can be used for cider production. Cider is made by pressing apples to produce juice, then fermenting that juice to make alcoholic cider. This process means that the size, shape and external appearance of the apples have no relevance in determining their quality and suitability for sale. However, if there are significant quantities of bruised and damaged fruit that are stored for a long period before being processed into cider, then the overall juice quality could be reduced.

Juice companies should also be careful when accepting heavily decayed fruit. This is because the increased decay risk (with blue mould) will also increase the risk of patulin (a mycotoxin produced by some moulds) contamination of juice fruit after storage.

Prevention

Hailstorms are unpredictable and the damage they cause can vary greatly. Prevention is better than cure when trying to combat hail damage in your orchard. Hail netting can protect against hail damage. Both structured and drape netting can provide a degree of protection from severe damage. To spread the cost of netting,  plan to net small proportions of blocks every year, beginning with the most valuable blocks.

Diversifying your orchard location can also help to alleviate some damage, as not all blocks are located together. Hailstorms usually come in cells that have bands of hail. In some cases, orchards in different locations will not receive any hail.