Blossom thinning

Besides the direct use as herbicides, one specific use of phytotoxic essential oils could be for chemical thinning of fruit trees. In initial trials with a commercially available clove oil-based herbicide (Matran, produced by EcoS MART Technologies Inc), apple blossom thinning effects were observed however, extensive leaf and fruit russeting was also observed, with effects dependent on concentration and the apple cultivar tested [27]. While the initial results are promising, further studies will be required before such herbicides can be used as chemical thinning agents. 

Naphthalene acetic acid is used to thin apple and pear blossoms and to control apple and pear preharvest drop (10). It also is used to induce flowering in pineapple, but conversely inhibits sprouting in potatoes, sweet potatoes, and turnips (Brassica rapd) (23). It also is used to promote rooting in... 

The seeds of the opium poppy are sown in October in well-cultivated soil. The seeds germinate in the fall, and the seedlings may be an inch high when snow falls this protects them from freezing. In the spring, when the plants have attained the height of 6 in., the fields are cultivated and the plants thinned to stand about 2 ft apart. The poppy blossoms in April or May, and the capsules mature in June or July. Each plant bears from five to eight capsules. 

To sum up - it would seem that reduction of the on year crop by blossom or fruit thinning with growth regulators remains the most practical way of controlling biennial bearing in apples but we still need more reliable and consistent fruit thinning agents. 

Thinning means the removal of excess blossoms or fruits. The aims of thinning are firstly to prevent biennial bearing and secondly to improve internal and external fruit quality. 

The number of blossoms can already be reduced when pruning the tree, by heavier pruning of the older spurs. So as not to stimulate growth urmecessarily, however, the tree should not be pruned too severely. There are several different ways of performing the thinning operation in organic fruit production ... 

Excess buds or blossom clusters are removed before flowering using the thinning machine. In this way the strain on the trees is reduced at an early stage (breaking the biennial bearing cycle). 

Frequently only one fruit is left per blossom cluster. It is better, however, to remove some blossom or fruit clusters completely (because the tree is then likely to produce flower buds at that point) and to leave 2 or 3 fruits on the remaining clusters. In this way the shoots from which all clusters have been removed have the assimilates available for producing flower buds. Nor is there any inhibition of flower bud production by phytohormones (which are synthesized in the seeds of the young fruitlets). Biennial bearing can thus be reduced by hand thinning an at early stage. 

The centre blossom often gives to poorly shaped fruits, which should be removed when thinning. 

Areas of application Mode of action Remarks Aphids, pear suckers Direct insecticidal action is only moderate, dissolves honeydew Russeting can occur under dry weather conditions Spraying at apple blossom time has a thinning effect... 

Naptalam itself in special formulation is suitable for peach thinning during blossoming. 

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