Limb Dieback / Leaf Drop

Finger Limes can and will shed leaves and defoliate at times, this may be a natural defense against many things, or simply the plant is under too much stress. I have witnessed both scenarios. Finger Limes can defoliate completely and survive,  but defoliation may indicate some serious problems. The Finger Lime has the ability to photosynthesise all the way down the stem, I have had a plant completely bare of leaves after I stressed it to see how little water it would require, to have it burst with new growth the next spring.

The shedding of leaves is a first line of defense in a stress situation for most plants. Leaf shed reduces evaporation loss during dry periods, I have also noticed that out of season flowering can occur simultaneously with defoliation.

Finger Limes can have branch dieback sometimes, and that can sometimes affect the whole plant. This may lead to the plant dieing, or never producing any fruit. Usually it will just be the end of a branch, or a tip. I have experienced scale and sotty mold and badly affected branches have had dieback some months later. The healthier the plant the less susceptibility to dieback or leaf drop. Healthy soil is the backbone of healthy plants.

Here are some tips to help prevent leaf drop/dieback.

– Plant Shock – Moving or changing the environment too quickly. I have plants growing in full sun and in full shade, but moving them from one to the other too quickly shocks them.

– Too much nitrogen fertiliser in Winter – leaf drop can be a symptom of over-fertilising. I use Terra Firma (BFA certified pellets), once at the beginning of Spring and once in Autumn, i also use Natrakelp as a foliar spray.

– Keep the soil moist, but be careful not to over water. It’s not so easy to observe wilt in finger lime, the leaves are too small, the first sign I have of lack of water is a little leaf drop and dry soil.

– Check to see if the plant is grown from seed or is grafted onto rootstock Poncirus trifoliata and troyer citrange rootstock (most common Finger Lime rootstock), which can be susceptible to Phytophthora

The following is an extract from the Primary Industry Resources South Australia. It is in relation to the Sunrise Lime, not specifically Finger Lime.

“During spring 2000 a twig and limb dieback was observed in Sunrise Lime in several districts. In general, the first symptom noted was the wilting of leaves and death of branches, up to 1cm in diameter, although this symptom was actually preceded by the (often unnoticed) death of smaller twigs and shoot tips. While most Sunrise Lime trees in each affected block showed symptoms, only some branches on each tree were affected, with adjacent branches apparently
healthy and often showing growth flush. The causal agent for the disease has been identified as a Phoma sp.

PIRSA – Australian Native Citrus