Paraffin oils increase the June fruit drop

The cultivation of apples requests the regulation of the yield (thinning), to have continuous yields and a good quality. Paraffin oils can favor the June fruit drop. However, their effect is different on the different varieties and is affected by different factors.

The regulation of the yield:
- Through the winter cut.
- Thinning during the blossom (mechanically or through acid products); lime sulfur, used for the regulation of fungi, has thinning side effects.
- Manual thinning.

Fundamentals:
- Through the June fruit drop, the apple tree regulates the amount of fruits on the tree on its own, to some extent.
- The fruit drop can be affected by pesticides, which work with hormones, or herbicides (i.e. Brevis).

Agents applicable for organic fruit growing:
- Oily substances, which cause a photosynthesis-shock.
- The ideal doses depends on the agent; differences exist also regarding the plant tolerance.
- The thinning character of the oily substances acts the most on a fruit size between 12 and 15mm.

Effects/side effects:
- Both effects and side effects depend on the specific variety.
- Red Delicious and Nicoter/Kanzi® and partially also Golden Delicious reacted very heavily on the thinning with paraffin oils in our tests, followed by Braeburn, Cripps Pink and Gala.
- The variety Fuji, instead, showed the least effects.
- The effects of the oils can be influenced by the doses per hl, the number of applications, the timing of the application and the technique.
- Since the lower parts of the tree are shadier, many more fruits fall in these lower parts.
- With varieties reacting heavily on the oils, a later application on a fruit size of 25mm might be better.
- Shade (i.e. through hail nets, cloudy weather) increase the effect of the oils.
- Sulfur-containing pesticides, mainly lime sulfur, increase the effect of the oils.
- Strong growing trees drop more fruits than weak growing trees.

Tolerance of the plants:
- Only with Golden Delicious, damages (russetting) were observed.
- Some damages on the leaves, which did not have effects on the quality of the fruits or on the bloom of the subsequent year.

Alternation:
- The method can reduce alternation and can have a positive effect on the bloom of the following year.

Documents

	Paraffinöle fördern den Junifall () Kelderer M., Lardschneider E. (2016). Paraffinöle fördern den Junifall. Obstbau Weinbau 53, Nr. 5, 9-11.
	Neue Wege für die Ertragsregulierung im (Bio)Apfelanbau. () Kelderer M., Lardschneider E. (2016). Neue Wege für die Ertragsregulierung im (Bio)Apfelanbau. Besseres Obst, heft 5/2016, 7-9.

Details

Activity type

Publication in technical journal

Activity work package

Reduction in pesticide residues

Activity number

Laimburg - WP3 - A28

Activity contact

Dr. Markus Kelderer
Laimburg Research Centre
Laimburg 6 - Pfatten
I-39040 Post Auer (BZ), Italy
[email protected]

Activity partner

Laimburg Research Centre

Activity country

Italy

Last edit

01-06-2018