Hail is a common meteorological phenomenon that is constantly present with high frequency and severity. It usually occurs during the "warm months of the year," starting from May through August. The highest hail frequency occurs during May and June, but in a broader sense, it can happen even earlier, from the end of April to the end of August. Hail usually appears in the afternoon hours, around 1:00 AM. until 8:00 AM. and lasts for a maximum of 10 minutes. Even in such a short time, hail damage worldwide exceeds 1 billion euros per year. Damages in Kosovo exceed one million euros per year. The occurrence of hail in Kosovo varies depending on the region and usually occurs every 3 years, but sometimes it can occur up to 3 times within a month (Gjilan Region) in June 2018. The areas affected by hail include narrow strips and surfaces. The damage is significant, especially to vineyards, orchards, and some fruit vegetable crops such as peppers and tomatoes. Hail directly affects quality and causes yield loss. However, for example, in apple orchards, hail causes more damage in quality than quantity.
Hail appears from the end of April until the end of August. Usually, in practice, the insurer's obligation begins when 50% of the petals fall from the flowers of the same variety and if they are not harvested within 10 days after the end of the harvesting period. Hail can damage the fruits, leaves, and branches of the apple; however, the insurance usually only covers the damaged fruits, even though the leaves, buds, and branches play a very important physiological role in the apple's vital activities.
Findings related to hail risk in apple orchards:
1. Hail causes more damage to apple quality than to yield, but quality damage does not exceed 50% of revenue.
2. The impact of hail in some cases is considered minimal because if it occurs from mid-May to early June, hail will thin out the apple fruits, so farmers will not need to intervene chemically or manually to remove at least 30% of the excess fruit.
3. Other findings that affect the amount of hail losses:
3.1 Different apple varieties respond differently to the intensity and frequency of the hail;
3.2 Hail is usually accompanied by storms, so hail attacks only one side of the apple row direction in apple orchards
3.3 The size of the hail granule is very important because the larger the granule, the greater the damage caused by hail.
3.4 Fruit density plays an important role, because if more fruit is produced, the protection of the fruits is higher, as the fruits overlap each other, etc.
3.5 The position of the fruits is very important for the impact of hail because the fruits located in the higher parts of the trees are more exposed to hail than the fruits located on the lower parts of the apple trees. Hail attacks the higher positions of the trees so that the fruits located in the lower parts of the tree will be covered by the fruits located at the top.
After occurrence and hail damage, apple fruits will be classified into the following classes:
Class I - This class includes superficially damaged fruits, and the damage is no greater than 1 cm on the surface of the fruit.
Class II – This class includes apple fruits with a larger surface area damaged and deep damage to the fruit surface up to 2.5 cm in size.
Class III – This class includes apple fruits that are severely damaged and whose fruits can only be used for industrial purposes.
Grade I
Class II
Grade III
Methodology for assessing hail damage
There are several methods used by agronomists for assessing hail losses. These methodologies are based on diagonal "X" or "Y" methods that allow the assessment of losses in orchards. These methodologies follow the following steps:
- The location attacked by hail must be determined precisely
- Depending on the methodology, agronomists must take branches from 2 apple trees diagonally (X or Y) in each segment. The branches should be at least 1m long.
- All apple fruits should be counted on every branch, and those fruits affected by hail should be calculated to find the percentage of damage per branch
How can farmers mitigate the risk of hail?
There are two agronometric methods for hail protection or loss reduction:
- The installation of an anti-hail net has several advantages: it protects the apple fruit from hail; it protects the fruits from sun exposure, especially some types such as Gran Smith. Thus, the net helps improve the quality of the fruits; it protects the fruits from insects, so insects do not bite the fruit. Meanwhile, the high price required to install the nets, ranging from 9,000 to 18,000 EUR depending on the quality of the hail protection system, is considered a drawback.
- Every apple fruit affected by hail is accompanied by apple scab (Venturia inaequalis). At the time the apple orchard is hit by hail, the farmer must immediately treat their apple with copper-based (Cu) preparations.
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