Sanjose Scale in Apples
Sanjose Scale is one of the pest of the apple tree and also appears on fruit too. It is also a major pest of peach and pear tree. It has widely spread through the areas of Himachal Pradesh. It is a unique appearing insect and indirect pest of apples. It is a type of sucking insect producing discolorations by injecting a toxin into the plant. Scales may be from 1/20 to ¼ inch in diameter and are normally found on the twigs and branches of the trees. They are also found on fruits making round red colored dots making it a shabby look. Scale insects feed by sucking plant sap resulting in poor growth. It remains active during the growing stages that is from March to November. If it is not controlled the tree can die in a couple of years.
Sanjose scales overwinter as immature scales. The females do not lay eggs, yellow alive crawlers are seen during the spring. These crawlers secrets wax to keep themselves safe from pesticides. Young scales can settle on the developing fruit as well, usually on the blossom end. The body of adult female is yellow and is covered with a rounded dark gray scale up to two millimeters in diameter.
To control and eliminate scale from apple tree one will need to take several steps;
First of all prune off heavily infected branches from apple tree. The pruned off branches should be either burnt or removed from the orchard. The orchard and tree debris should be kept clean in order to avoid the infestations. Apply dormant spray oil with insecticide labeled for Sanjose scale. It should be applied when the trees are under dormancy. The spray should be done in efficient manner so that it covers the whole canopy of the tree in other words spray until run-off starts. The adults as well as crawlers secrets wax layer to prevent themselves from pesticides. So it is necessary to use oil as it makes a film on every part of the tree. It prevents the insect from breathing resulting in death of the insect.
Horticulture mineral oil can also be applied @1.5% to 2.0% from bud burst to pink bud stage to control the crawlers. This is an efficient way as the life cycle of Sanjose scale starts from this stage.
Natural enemies that feed on San Jose scale include two predaceous beetles, the twice stabbed lady beetle, (Chilocorus orbus), and another small beetle, (Cybocephalus californicus.)
Parasites include Aphytis and Encarsia. These predators and parasites are helpful in reducing scale populations, but broad-spectrum insecticides used during the growing season for other pests disrupt this natural control, and scale populations can build as a result. Low winter mortality due to mild temperatures will also permit a buildup of scale populations.