Management of Young Coffee Trees

Well managed trees have single stems and are uniform in size

Research has shown that coffee trees are slow to establish in the field due to their slow growth rates and poorly developed root systems. Successful establishment requires very attentive management. Poor management in the first year can delay cropping by one to two years, affecting long-term profitability.

This article discusses the six critical management operations in a coffee plantation from the seedling stage until trees are mature and bearing. The six operations are weed control, fertiliser application, pest and disease control, irrigation, tree shaping and control of early flowering.

Weed Control:

The experiences of several coffee growers suggest that the biggest problem when establishing coffee trees is weed competition. The trees have poorly developed, shallow root systems, with 80% of the roots in the top 30 cm of soil. This means they cannot compete with most weed species for nutrients and water. Weed competition slows their growth significantly and if severe enough will suffocate them completely. Fortunately you can overcome almost all weed problems with good management. In a newly established plantation give weed control high priority and make it part of your management program. Keep a 50 cm weed-free strip either side of the plants.

Pre-emergent herbicide:

Under shade i.e mulch, soil temperature is lower, mulch decay is faster, and soil respiration rates are higher.

Immediately after planting apply a pre-emergent herbicide or mulch in a 50 cm band either side of the plants. When used as a direct spray, Goal® (registered in Queensland only) has been very successful as a safe pre-emergent herbicide. It suppresses germinating weeds for up to three months, allowing coffee seedlings to establish their root systems without competition. Apply it according to the label instructions.

Mulch:

Research indicates that coffee trees respond well to mulch in the first year of planting, especially in hot, dry environments on shallow soils. A good mulch cover prevents weeds establishing, lowers soil temperature, retains soil moisture, increases organic matter in the soil, and reduces the need for herbicides, all of which provide a better environment for root growth. Maintain a mulch layer 5 to 10 cm deep for at least 30 cm around each plant. Take care not to allow green or fresh mulch material to contact the stems of the young plants as it will burn them. Straw mulch ensures minimum weed competition, reducing the need for herbicides. It also improves the environment for surface root growth.

Post-emergent herbicide:

Use post-emergent systemic herbicides to spot-spray weeds which come up in the weed-free strip close to the plants and to kill weeds encroaching along the edge of this strip. The most useful registered herbicide for this is glyphosate (Glyphosate®, Roundup ®). Apply according to the label recommendations. Young coffee plants are sensitive to spray drift from these herbicides so take care when applying them. Use covered sprayers (undertree weed atomisers), rotating wick wipers and low pressure control droplet applicators to avoid spray drifting onto trees. Glyphosate damage in coffee can he recognised by the deformed growth – leaves become yellow, thin, elongated and strap-like.

Past experience suggests that the herbicide paraquat, found in Grarnoxone ®, Spray seed® and Shirquat® is unsuitable for use in coffee because it can cause severe damage to the trunks of young trees, leading to ringbarking and death months or even years afterwards. Plants which have become problem weeds in North Queensland are Mexican white eye (Richardia brasiliensis) and the climbing vines glycine ( Glycineclandestina) and siratro (Macroptilium atropurpureum). If these are likely to become a problem they should be controlled before the coffee trees are planted. No chemical is registered for controlling these weeds in coffee plantations, so the only control once the trees are planted is hand-weeding.

Note:  Ringbarked seedlings result in tree death. Ringbarking has several causes: fertiliser or fresh mulch contacting and burning the bark; the herbicide paraquat contacting young stems; wind blowing seedlings around and fretting the bark against the soil.

Establish windbreaks, ground cover and a one metre weed free strip around trees

Ground cover:

Plant a ground cover between the tree rows. This not only helps control erosion and lowers soil temperatures, but improves the micro-environment around the trees and can be used as an undertree mulch. Choose a cover that is not too aggressive, that does not climb or spread, and is easy to kill with appropriate herbicides. Slash it regularly to avoid seeding. As long as a weed-free strip is kept within the coffee row, competition between the ground cover and the coffee trees is kept to a minimum.

Recommended ground covers include bracharia grass (Brachiara decumbens) and pinto peanut (Arachis pintoi) in North Queensland and carpet grass (Axonopus compressus) and kikuyu (Pennisetum clandestinurn) in northern New South Wales. Apply extra fertiliser in the inter-row while the ground cover is being established so that it does not compete with the coffee trees for nutrients. Once the ground cover is established, the nutrients in the slashings should reduce the fertiliser requirement. Inter-row cropping has not been successful.

Source:  James Drinnan and Ted Winston