The Zimbabwean Gardener Issue 15 Summer 2015/2016 Low res | Page 21

Fruit tree care

Fruit tree care in summer

By Dr C Nyakanda

Doctor Chris Nyakanda tells us how to get the most out of our fruit trees in the garden.
During this period, most mature fruit
trees are laden with fruit or are in the
post-harvest phase. Conditions may be
hot, wet and humid. Whilst continuing
to be wet, temperatures may gradually
decline. Your major objectives in these
months should be the following:
1. Improve fruit yield
2. Keep fruit and trees disease-free
3. Before it enters the rest phase, prepare
the tree for the next season

Fruiting management

Most likely, you have completed
fruit thinning at this stage. Continue
fruit thinning for late varieties as this
increases fruit size, quality and colour;
it also reduces breakages and increases
the regularity of fruit bearing. In general,
plums, peaches, nectarines and pears
benefit immensely from fruit thinning.
Citrus, mango, grape clusters and
nut trees also benefit from thinning.
With mango trees, thin to one fruit per
flower stalk. Remove small, diseased
or misshapen fruit first. Remove dead
flower stalks to reduce disease and
increase uniformity of the fruit. Reducing
fruit load is important in young trees to
avoid tree stunting. Generally, across all
fruits and nuts, reduce each fruit cluster
to one fruit.

Watering

Water trees during dry spells. Water
evenly to avoid fruit drop or fruit
cracking that is caused by uneven
growth. At a household level, watering
needs can be determined by the feel
and appearance of the soils at the root
zone. Soils that provide less than 25%

moisture generally feel dry, form weak
balls when squeezed several times, and
do not leave finger impressions. Their
soil grains stick loosely to the hand,
and these soils leave very little water
staining.
As a rule of thumb, apply 30 litres
of water per week to mature trees.
However, be aware that water
requirements and frequency of
application may vary drastically. For
instance, container fruit trees may
require watering every other day, yet biweekly or monthly intervals may suffice
for trees grown in the ground. A mature
litchi tree may need upward of 200 litres,
bi-weekly, during a rainless summer.

Mulching

Mulch material is plentiful at this time
of year, so gather a year’s supply and lay
the mulch immediately. Mulching your
fruit trees is extremely beneficial in the
following ways:
1. Reduces frequency of watering
2. Reduces disease incidence
3. Smothers weeds
4. Smartens up the orchard
Mulch materials include in-situ, closely
clipped grass turf, maize stalks, grass
cuttings, hedge clippings or shredded
tree pruning. However, do not mulch
close to the tree trunk, or too deeply, as
this causes collar rot, which ring-barks
your tree and eventually kills it.

Fertilising

Fertiliser application at this time of year
is done primarily to replenish substance
to the soil that has been lost during

fruiting, and to maintain growth activity.
Apply compound fertilisers with equal
amounts of nitrogen, phosphorus and
potassium. Ideally, if using Compound
‘J’ (also termed ‘Fruitfert’ or ‘Coffee
fert’), split and apply two-thirds in the
period leading up to fruit harvesting;
apply the last third after harvest. Apply
in combination with small amounts of
organic manures. Do not incorporate
fertilisers into the soil lest you damage
superficial roots.

Pest and disease control

Diseases common in wet conditions
include fungal rots (e.g. brown rot),
bacterial rots and mildews (downy and
powdery mildew). Pests that flourish
include fruit flies, aphids and scale
insects.
It is very important to understand exactly
what chemicals you are using. It is best
to seek help in identifying the pest or
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