Strap Vanda Culture
Strap-leaf Vandas are mainly derived from Vanda sanderiana and other Vanda species. To grow strap-leaf Vandas, it is most logical to review the habitat of Vanda sanderiana and other Vandas in nature.
The Vanda plants have proliferated in rainforest biome and therefore has evolved to adapt to high humidity. Thai growers capitalized on this fact and has grown strap leaf vandas to perfection by providing moisture below the plants in form of water throw.
The canopies of the host trees (Ipil, Anonang and Dipterocarps) are half dense and half open letting diffuse light in for the plants… so that 50 to 70% net are usually used in its cultivation.
Where Walingwaling grows, it usually rains late afternoon or during night time. This contradicts the baseless superstitious belief being propagated that if you water the plants at night, the plants will get sick!
Some of the inexperienced growers will even tell people about the unverified growth of microorganisms at night in relation to watering. We have proven more than 4 decades ago through a controlled experiment that night watering does not cause infection of Vanda leaves much less its demise. The Vanda Root System
Vanda roots ramify on the tree barks. The green tipped, white roots of Vandas grow on the moist sector of the tree trunk exposed. The green tip (purplish for some varieties) of the Vanda continues to grow forward, while the white part, which are actually dead epidermal cells catch up as the tip advances in growth.
The white sector of the Vanda roots is called the These dead epidermal cells contain hygroscopic materials responsible for absorption of moisture from humid air. This explains why the orchids in nature do not dry out easily while those in nurseries need constant watering (root insufficiency). Some orchids survive through 6 months of dry season because of the efficiency of the velamen to procure water for the plants directly from the ambient air.
Healthy Vandas maintain white velamen. When the velamen is infested with algae as in most nursery-grown Vandas, the opportunistic algae benefits directly from the liquefaction of the hygroscopic materials in the velamen. The algae grabs the water in the velamen for its own growth and reproduction while the plant dries up.
Chronic algal infestations result in dehydrated plants. To balance the dehydration, the plant shed some of its waterusing sectors, the lower leaves. The lower leaves turn yellow one by one going up and later shed, resulting in ugly unmarketable leggy plants.
The green growing tips of Vandas are unprotected (no root caps). Spraying strong fertilizers result in plasmolysis of the root tips. The fertilizer burns the root tip and the velamen catches up as the tip stops growing. This trauma results also in lowerleaf shedding, too.
Fertilizers at 200ppm N level can be used effectively for Vanda feeding but “aggressive feeding” invented by an Agriculture undergraduate should not be used. The Aggressive Feeding program is expensive and results in the precipitation of its main components and clogs the sprayers with sulfates and phosphate precipitates. The plantsget a bonus of burnt root tips. The aggressive feeding program has damaged a nursery in Quezon City resulting in total devastation of all orchids and expulsion of its “consultantor chidologist”.
The deadliest pest of Strapleaf is the Schlerotial Rot. This microorganism is usually introduced through rice hulls and rice hull dusts although old rotting logs may carry them, too.
Other fungal and bacterial diseases may be prevented by sufficient Calcium in the feeding system. Concomitant spray of Silicic Acid after Calcium nitrate spray prevents pests and diseases.