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Rubber Pest and their Control |
Rubber can be affected by diseases which may become serious if left unchecked. Early disease detection helps prevent their spread and damage both in rubber nurseries and plantations.
Diseases that affect the rubber trees are classified according to the part of the plant affected, namely, foliar (including nursery seedling), stem or branch, panel, and root diseases. Disease management can be accomplished by proper cultural and management practices and whenever appropriate, by integrating fungicides if extremely necessary. Table 1 presents the list of rubber diseases and the corresponding recommended control measures.
A. Foliar Diseases
1. Bird’s eye spot or Helmisthosporium leaf spot.
Causal organism:Helmin-thosporium heveae.
Affected leaf surface has numerously-scattered small, circular spots with transparent centers and distinct brown borders. Infected young leaves are blackened and wrinkled; older leaves have necrotic tissues which produce shot holes caused by some tissue drop-offs.
2. Anthracnose leaf spot.
Causal organism: Colletotrichum gloeosporioides
Infection starts from the edge of the leaf and moves toward the center. This disease produces brown- to straw-colored lesions (injured portions) that are usually a few centimeters in diameter. As the disease advances, the infected portions or lesions merge to from concentric lines, thus, malformation occurs. The disease is found mainly on young budded plants and young trees. Rain and high humidity favor disease development.
3. Powdery mildew or Oidium leaf disease.
Causal organism: Oidium heveae.
The disease is characterized by white, cotton-like, hairy borders along the lesions. The mycelia (thread-like structures) of the pathogen are visible even without the aid of a magnifying lens. In the most advanced stage of the disease, the entire lamina is covered by the mycelia, then leaf dries, and finally falls off.
The presence of numerous immature leaflets on the ground indicates infection. By the time this is noticed, the causal fungus is already well entrenched. Unfolding leaflets about 5-cm long are shriveled and blackened progressively from the leaf tip. This causes the leaf to fall, leaving the leaf stalks for a while still attached to the tree.
The shiny filamentous colonies of Oidium are clearly visible on the freshly-fallen leaves. These are associated with the outbreaks of the yellow tea mite (Hemitorsemus latus). Careful examination may also reveal the mites and eggs beneath the leaf surface.
4. Fusarium blight.
Causal organism: Fusarium solani.
It is indicated by the death of infected tissues. Early indication is the presence of irregular, brownish lesions, which enlarge later on. As the disease progresses, the infected leaf eventually withers and a pinkish, shiny, cotton-like, hairy growth is evident on the infected area beneath the leaf surface. Symptoms on the stem cause panel necrosis.
5. Zonal leaf spot
Causal organism: Rhizoctonia solani.
Symptoms of this disease include small circular spots with yellowish margins. Black outgrowths are found in dead areas of the leaves. Portions with advanced infection become papery. Black outgrowth found in advanced lesions form into several rings with a common center. |
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Corn Production Techno-Guide (English) |
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Corn is second to rice as the most important crops in the Philippines. In spite of the fact that almost 3 million hectares are devoted to the cultivation of this crop annually, current production is not enough to meet the local needs due to low yield. In fact, since five years ago, corn importation of the Philippines has been on the increasing trend.
Among the major factors responsible for low yield are the use of low yielding varieties and inadequate cultural management particularly in the area of fertilization, planting density, insect, diseases and weed control, etc.
This production guide presents the consolidated technologies designed to overcome the above mentioned problems which were based on the results of various trials conducted under the corn high impact project funded by the Department of Agriculture-Bureau of Agricultural Research (DA-BAR). It provides a simple but practical guide on adequate cultural management practices of corn for the Arakan Valley and in areas with similar growing conditions. It is hope that agricultural extension workers and farmers will find this guide useful and hopefully, the utilization of this technologies would considerably increase the current average yield of corn.
Following are the basic steps to successful corn production:
Cultural Management Practices
Land Preparation
 Prepare the land thoroughly by plowing twice, each plowing followed by one harrowing. Thorough land preparation minimizes growth of weeds, enhances water retention and ensures good germination of seeds and growth of seedlings. Other Land Preparation Technology Options
Minimum Tillage Practices
- Slash tall grasses and corn stover or harrow using animal-drawn harrow
- Make furrow at recommended distance (65-70cm) using animal-drawn plow
- Apply 50% of N requirement plus all P and K requirement depending on soil analysis
- Plant seeds at a distance of 20-25 cm at the rate of 1 seed/hill
- Spray power herbicide at the rate of 6-8 li/ha after planting
- Side dress the remaining N fertilizer (urea) by target method 25-30 DAP
Zero Tillage Practice - Slash tall grasses and corn stover or harrow using animal-drawn harrow
- Plant seeds using dibble method (todak or tagad).
- Apply basal fertilizer by todak or tagad method also (todak for fertilizer to be made side by side with the todak for seed)
- Spray round-up at the rate of 4-6 li/ha mixed with herbadox at the rate 2 li/ha and atrazine at 1 kg/ha (CP) after planting.
- Side dress the remaining N fertilizer (urea) by target method 25-30 DAP |
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