Protecting fruit trees
While fruit trees can provide the most economically rewarding return for the labour and effort required to establish and maintain them, much of this will be directed toward protecting them against birds, insects, and other organisms. Since the organic philosophy is based upon promoting biodiversity and establishing harmonious relationships with nature, the strategies used to protect fruit trees need to be more sophisticated and enduring than those which only seek to remove or eliminate garden competitors. An integrated approach is recommended for coping with persistent fruit pests. In the first instance, ensuring the health and vitality of soil helps to support strong plants and lays the foundation for a balanced garden ecosystem. Because established fruit trees deplete soil nutrients, it is important to avoid the common practice of immediately replacing deceased specimens with new trees of the same variety.
Immature fruit trees grow poorly in mineral deprived soils. They are also more likely to be damaged by soil pathogens which are resisted or tolerated by established trees. Young peach trees are particularly sensitive, and may be poisoned by the residual root chemicals of older trees. Garden hygiene plays an important role in protecting plants from many types of disease and pest infestation. This involves careful monitoring of introduced garden materials, routine clearance of fallen fruit, and direct removal of any damaged or infested fruits. Maintaining a diversity of acclimatised fruit species, varieties, and other plants will promote natural competition between pests and predators. This competition helps discourage and prevent the unchecked proliferation of pest species which cause damage to fruit bearing plants and their crops.
Most regions support several bird species which feed heavily on ripe and developing fruit. The most devastating are often larger and highly intelligent birds, like parrots, and crows which can arrive in substantial flocks around the time of fruit ripening. These strong competitors have claws to hold and beaks which easily rip through the protective skin of fruits such as avocado, mango, and passionfruit. On account of their intelligence, strength and tenacity, these creatures can be extremely challenging to discourage. Smaller species like finches and sparrows are always attracted to softer fruits, and berries. They often arrive to feed at dusk or dawn and will quickly ravage these crops unless some strategic visual deterrents or physical barriers are installed to restrict their access.
Fruit cages, wire mesh, and nylon netting are all suitable for protecting organic fruit crops. Many organic fruit growers rely on permanent fruit cage structures with removable netting. This enables an effective barrier to be established immediately prior to crop ripening. During the remainder of the year, the netting can be removed to enable birds to move freely about the trees and bushes. This encourages nectar and pollen collecting species like honey eaters and those which feed on potentially destructive insects and larvae. Without their assistance, many cross pollinating species struggle to bear fruit, and among those which do, the likelihood of insect related crop damage is significantly increased. Large fruit cages provide suitable protection for most soft tree fruits and the vine and bush species including cultivated berries, currants, and grapes. Small, portable cages or cloches can be used to protect individual bunches of fruit. This approach is labour intensive, but seems to work efficiently on fruits which ripen slowly or at different rates on the same plant.
Most of the commonly applied bird deterrents are based on creating noise or visual signals which threaten and discourage birds from approaching a potentially attractive food source. Scarecrows are a traditional favourite and have been used to protect grain and fruit crops over many centuries. On commercial properties, scarecrows are often combined with randomly timed firings of blank ammunition and other non destructive explosions. High pressure water jets can discourage many smaller species but are rarely effective for the larger parrots, crows, or geese which are all notorious and persistent scavengers of fruit.
Another innovative strategy is the kites and wooden models which mimic the shadows cast by hawks, falcons, and other birds of prey. Once again, these can be useful for frightening smaller birds but larger and more intelligent species are unlikely to be discouraged for an extended period of time. Many organic gardeners and growers will invent their own unique bird deterrents, sometimes creating these from recycled household items and discarded rubbish. These range from simple mobiles of shining tinfoil and silver discs suspended from tree branches to highly complex electronic gadgets which emit shrill sounds upon detection of movement. The success of these attempts will vary from region to region, depending on the species and quantity of birds and fruit alike.
In combination with other garden competitors and beneficial organisms, birds contribute to the total ecosystem and should never be eliminated through trapping, shooting, or poisoning. These violent and negative strategies are incompatible with the organic philosophy which always seeks abundance through maintaining the essential harmony and balance found within nature. For similar reasons, domestic cats are not suitable for discouraging birds in suburban gardens. Cats are an introduced species which breed quickly to disrupt the normal distribution of predator and prey. According to their predisposition, most cats are indiscriminate hunters, killing more often than is required to sustain themselves. While they may hunt some of the fruit eating birds, they will almost certainly include the valuable insect eaters and pollinators which are rapidly disappearing from many suburban locations.
Thoughtful growers understand that most fruit eating species play an essential role in their native environments, distributing the seeds for new growth. Because their impact upon fruit crops can be interpreted positively and at times, negatively, any decision or action that seeks to control bird populations must strike the correct balance between encouragement and deterrence. Initially, this can present a daunting challenge; however, time, careful observation and experience will ultimately make the task an easier one.
There are several mammal species which can feed heavily on fruit crops whenever the opportunity arises. Rats and mice both contribute to enormous agricultural losses. While the majority is related to grain destruction and spoilage, both species will be attracted to easily accessible fruit crops such as strawberry, passionfruit, and gooseberry. Fruit cages with narrow gauge steel meshing will prevent access to rodents and other fruit eating creatures such as squirrel, pigs, rabbits, even the odd fox, occasionally. These competitors can also be discouraged by the presence of hunting dogs, particularly those of the terrier family.
Terriers were originally bred to a size and character which enabled them to dig down and enter the burrows of ground dwelling animals such as rabbits, badger, and foxes. The smaller breeds are particularly useful for controlling rats without the constant use of traps and poisonous baits. Less common animals such as fruit bats and possums can be a significant threat to fruit crops in some areas. The heavy bodied fruit bats known as flying foxes are notorious in tropical and subtropical environments. Living in colonies, these intelligent and social animals can descend on fruit plantations in sufficiently large numbers to strip valuable crops and cause extensive damage to trees. Under these circumstances, frustrated growers often feel compelled to shoot or poison flying foxes. In an attempt to prevent this, researchers have looked at unique prevention strategies based on high frequency sounds and discouraging smells. Hopefully, these might prove effective and become widely available in the near future.
Possums are agile and adaptable tree dwellers, with a voracious appetite for green shoots, fruit, and sweet vegetables. Being largely nocturnal, local populations can be difficult to evaluate. Once again, the mainstream approach to possum control is an unfortunate combination of trapping, shooting, and baiting. Fruit cages can be effective for protecting organic crops; however trees can still be severely damaged by possums stripping green shoots and bark. Mature trees can be protected to a certain extent by sheet metal bands encircling their trunks. This prevents trees being directly scaled. In order for this strategy to be effective, other aerial access points such as adjoining trees, telegraph poles, fencing, and flat roofs must also be carefully secured.