Cultivar Notes
Aurora
Golden GalaTM
Aurora Golden Gala™ can be extremely productive
and therefore requires early and heavy thinning for acceptable fruit size. The
cultivar appears to thin relatively well with moderate rates of carbaryl. It requires
a follow-up hand thinning to space fruitlets 15-20 cm apart. Match crop load to
trunk diameter. Many young Aurora trees have been cropped too heavily, resulting
in small fruit, delayed maturity, poor colour, poor taste and generally poor quality
fruit. This cultivar responds well to Surround Crop Protectant particle film to
increase fruit size and improve shape and fruit finish.
Ambrosia
This
spurry upright growing cultivar has been successfully thinned in Ontario with
moderate rates of Sevin XLR. A well-thinned crop of Ambrosia finishes strongly
with regard to size and colour development. The picking window for Ambrosia is
narrow if the crop is to be held in long-term storage. Consult OMAFRA
factsheet Commercial Production of Ambrosia Apples in Ontario, Order 09-041.
Cameo
Trees can normally handle heavy crop
loads in a vigorous canopy. This cultivar has been shown to thin adequately with
Sevin XLR (1 L/1,000 L water) on established trees.
Creston
Creston
has been shown to over-thin easily with low to moderate rates of Sevin XLR. It
is a productive large size cultivar that requires two pickings.
Empire
Before
the application of NAA, make sure the king bloom fruitlet is set through a check
of sepal posture. Petal fall of king bloom can take place as early as 3-4 days
past peak pollination. If NAA is used too early (full bloom to petal fall), the
overall fruit size of unthinned apples may be reduced compared to treatment at
a stage when the king fruitlet is 8-10 mm in diameter.
Enterprise
Enterprise
appears to thin adequately with moderate rates of Sevin XLR.
Fortune
Fortune
is a large sized, highly coloured, dual-purpose apple that requires thinning to
avoid biennial bearing. Fortune requires a strong treatment of NAA in combination
with Sevin XLR. Experienced growers have reported success with 10 ppm NAA plus
1 L of Sevin XLR per 1,000 L of water.
Fuji
Fuji
must be thinned aggressively for best results. This cultivar exhibits strong biennial
characteristics and unthinned Fuji normally returns very little bloom the next
year. Mature trees usually thin adequately with combinations of Sevin and NAA,
but follow-up hand thinning of king fruitlets is usually necessary. Excessive
crop may prevent the fruit from maturing to premium quality.
Gala
Gala is relatively difficult to thin successfully, and requires aggressive
thinning on mature trees. NAA and Sevin at the rates listed for Golden Delicious
have given good results, if applied when king fruitlets are 8-9 mm. Combination
sprays of 6-BA and Sevin have also been very effective. Clusters must be thinned
to one fruitlet or king bloom by mid to late June to achieve best fruit size.
A follow-up hand thinning within 30 days of full bloom is normally required to
further reduce crop load.
Late thinning sprays may increase the production
of mummified fruitlets colonized by the fungus that causes black rot. Earlier
applications produce fewer mummies, reducing black rot inoculum, and maturing
fruit is less likely to be infected.
Gingergold
This
cultivar appears to be more sensitive to thinners than McIntosh, Northern Spy
and Empire. It can be over-thinned with high rates of NAA or strong combinations
of NAA and Sevin XLR or MaxCel and Sevin XLR.
Golden
Supreme
Unlike Golden Delicious, this mid-season Golden Delicious type
will thin adequately with 1 L of Sevin XLR per 1,000 L water.
Goldrush
Goldrush
requires a combination of NAA and Sevin XLR (10 ppm NAA + 1 L Sevin XLR per 1,000
L water). This cultivar is much tougher to thin adequately, but a well-thinned
crop will mature more easily.
Honeycrisp
This
cultivar seems to be more sensitive to thinning treatments than Empire. Thin Honeycrisp
cautiously, as it can easily become oversized and is very prone to bitter pit.
Where large fruit is a problem, it may be best to leave two fruitlets per cluster,
or space the fruit closer together. Use of growth regulators (such as 6-BA), which
enhance fruit size, may not be warranted for this large fruited cultivar. Use
no more than 2.5 ppm NAA with 1 L of Sevin XLR per 1,000 L of water as a starting
point on established trees. Many growers report good fruit size distribution when
the largest fruitlets are removed by hand thinning following the spray thinning
treatment. Honeycrisp is highly biennial in nature and may not return an adequate
crop year after year.
For a discussion on crop load and trunk circumference
with respect to thinning see OMAFRA
Factsheet, Commercial Production of Honeycrisp Apples in Ontario, Order
No. 05-047.
Jonagold
This cultivar thins
relatively easily and has good size potential when clusters are thinned to singles.
Most producers get adequate thinning with moderate rates of Sevin. Over-cropping
Jonagold may result in very poor return bloom and fruit may not mature to a premium
quality.
Shizuka
Shizuka thins similarly
to Mutsu/Crispin with moderate rates of Sevin XLR.
Silken
Silken
thins with 1-1.5 L of Sevin XLR per 1,000 L of water, depending on tree age. This
cultivar bruises easily. Evenly spaced fruit in the canopy is desirable because
it enables careful picking and handling.
Table
of Contents