ALMOND PEST Brown Mite, Leaffooted Bug, Stink Bugs || KHETI KA HISAB

 

ALMOND PEST 

1. Brown Mite

  Bryobia rubrioculus

Description of the Pest

The brown mite is the first to appear in the spring and is the largest of all the almond pest mites in terms of size. Numerous red, stalkless brown mite eggs overwinter on twigs, especially at the intersection of wood growth from the two previous seasons. The same time that leaf and flower buds open, eggs begin to hatch. After their initial molt, newly hatched mites change from scarlet with six legs to brown with eight legs, looking more like the adult. Adults have long, flat front legs.

The in-season generations lay their eggs close to conspicuous leaf veins on the undersides of leaves. Only during the chilly periods of the day do the mites eat. Around noon, they migrate off the leaves. The hottest parts of the summer are when they are not active. Between February and June, there are two to three generations per year.

Damage

These mites are typically not regarded as serious pests, and low to moderate populations may even be advantageous in the spring by acting as a food source for mite predators. Chlorosis can result from these mites feeding on plants, however leaves rarely drop. Usually only a few trees are affected by infestations.

 

Management

Ø Biological Control : Although brown lacewings and the western predatory mite are both potent predators, neither one by itself may be able to control brown mites. Use of certain pesticides, such as pyrethroids applied during the dormant season, can affect predator mites, thus it's crucial to avoid applying insecticides that eliminate these natural enemies.

Ø Organically Acceptable Methods : For usage on crops grown organically, certain oil sprays and biological control are authorized.

Ø Monitoring and Treatment Decisions : The delayed-dormant spray works best for reducing the number of brown mites. As part of the dormant spur sample, look for mites. An oil application is advised if more than 20% of the spurs are infected. When dormant treatments with oil are not applied, are applied too early in dormancy, or are applied with a rate of oil that is too low, there can occasionally be an infestation during a chilly spring. If there is indications of feeding damage (bronzing or stipling of the leaves) at this time of year, a spring oil spray can be used in this situation.

 

2. Leaffooted Bug

  Leaffooted Bug: Leptoglossus clypealis, Leptoglossus occidentalis, Leptoglossus zonatus

 

Description of the Pest

In almonds, the leaffooted bug is an occasional pest. The huge nymphs and adults have tiny, leaf-like enlargements on their hind legs, which give the species its name. Adult bugs measure about an inch long and have a flattened back and a slender brown body with a zigzag pattern across it in either yellow or white. On host plants close to orchards, the leaffooted insect overwinters as an adult in big groups. In March or the beginning of April, bugs that overwinter go from these locations into orchards in quest of food.

In strands of 10 to 15 eggs, which are typically found on the sides of nuts in almonds, adult females lay their eggs. Small nymphs that resemble freshly hatched assassin bugs emerge from the eggs.

Almonds include three different kinds of leaffooted beetles. The Leptoglossus zonatus is the most prevalent. The appearance of the three species is similar, with the exception that L. zonatus has two yellow spots on the pronotum slightly below the head, L. clypealis has a thorn-like projection on the tip of its head called a clypeus, and L. occidentalis lacks both of these characteristics. All three species feature a white zigzag pattern on their wings; in L. zonatus and L. clypealis, this pattern is more pronounced; in L. occidentalis, it is more subdued.

Damage

Despite being an infrequent pest in almonds, severe harm can happen in years when the weather and other factors are favorable. The embryo withers and aborts when adult leaffooted bugs feed on young nuts before the shell hardens. The nut may also gum up internally, leaving a bulge or gumming on the shell. It might also cause nuts to fall. Adult leaffooted bug feeding might still result in black patches on the kernel or wrinkled, crooked nutmeats even after the shell has hardened. For a longer amount of time during the season, varieties with softer shells, such as Fritz, Sonora, Aldrich, Livingston, Monterey, and Peerless, are more vulnerable to pest damage.

Be careful not to mix up damage from stink bugs with injury from leaffooted bugs. Both bugs gum up the hull of the nuts they damage by probing them with their needle-like mouthparts. Damage from leaffooted bugs typically happens in March and April, but damage from stink bugs typically happens in May and June. Finding the actual bugs or their egg masses is another way to tell one type of damage from another given how similar the symptoms are. For example, stink bug eggs are barrel-shaped and laid in clusters, whereas leaffooted bug eggs are laid end-to-end in strands.

 

Management

Ø Biological Control

Gryon spp. egg parasites frequently restrict leaffooted bug populations from reaching levels that are detrimental to the economy. However, because they are egg parasites, they are powerless to regulate the adult leaffooted bugs that overwintered and migrated into orchards in the spring.

Ø Monitoring and Treatment Decisions

During the months of March and April, stroll through the orchard to look for dropped nutlets (especially on vulnerable types), gummed-up nuts, and leaffooted bugs. The best warning sign of a potential issue is finding adult bugs, but because to their evasive nature and tendency to linger in treetops, this is challenging to achieve. Searching for nuts with egg masses or gummosis on their sides is a more practical strategy. If gummosis is present, make a cross-section of the affected area and examine it for a puncture mark made by the bug's mouthparts to make sure it isn't caused by physiological factors. Finding abandoned nuts on the ground is the most straightforward monitoring technique. However, using gummosis and nut drop as the basis for therapy also means that the dispersing insects might have already moved since there can be a 7–10 day lag between when feeding occurs and gummosis and nut drop.

 

3. Stink Bugs

·        Green stink bug: Acrosternum hilare

·        Redshouldered stink bug: Thyanta custator accerra

·        Uhler stink bug: Chlorochroa uhleri

Description of the Pest

The green stink bug is the one that infests almonds the most frequently. Bright green adults of green stink bugs have a yellow or orange lateral edge that extends the full length of the beetle. Green, black, and orange colors are mixed in the nymphs of green stink bugs. The green plant insect and red-shouldered stink bug are less frequent and smaller in size. The redshouldered stink insect measures 0.33 inches in length and has a triangular form. Its color is mostly green with a thin red band across the shoulder; occasionally, the band is not there. A brown phase also exists, which is typically found in overwintering insects. The Uhler stink bug is significantly bigger (0.4-0.6 inch in length), dull to bright green, and slightly longer.

Stink bugs frequently grow in weeds or field crops before migrating into almonds in the spring as their hosts' hosts wilt. The green stink bug is an exception, as it spends the winter inside the orchard. These stink bug eggs are barrel-shaped, placed in clusters, and have concentric dark rings on top. They are frequently observed on the almonds' hulls. Because they lack wings, immature stages resemble adults but are smaller, rounder, and shinier. They have numerous color marks that can differ from those on adults.

 

Damage

The green stink bug is typically responsible for almond stink insect damage. Due to broad-spectrum dormant pesticide treatments, this bug was kept from becoming a problem for many years by preventing it from overwintering in almonds. In orchards where organophosphate, carbamate, or pyrethroid pesticides have not been used for three to four years, particularly in the lower San Joaquin Valley, there have been an increasing number of complaints of stink bug damage more recently.

Stink bugs typically cause damage between May and July when they stick their straw-like mouthparts through the hull and into the kernel. The only difference between this damage and that caused by leaffooted plant pests is that it occurs later in the growing season and does not induce nut abortion. Instead, strands of slime, known as gummosis, that leak from the puncture site can be used to identify broken nuts. When nuts are harmed by bugs, the kernels either become wrinkled and crooked or, if they have already hardened, have a black mark where the hole was made.

Management

Keep an eye out for gummosis on the almond hull's surface from May through July. If a puncture mark is present on the kernel, cut a cross section through the affected area to separate physiological issues from bug damage. Stink bugs are not very mobile, therefore damage is frequently found in groups, frequently with the bug or an egg mass remaining nearby.

Stink bug treatment thresholds do not yet exist. Based on the extent of the damage and orchard history, decide whether to spray. For any pest, one dormant (for green stink bugs) or in-season broad-spectrum insecticide (for all species) every three years is usually enough to prevent financial harm. Consider preparing an in-season spray with one of the following items when only low-risk products have been utilized and the damage levels caused by stink bugs become intolerable. Consider using one of these treatments in a tank mix with a neonicotinoid insecticide like acetamiprid (Assail) if the population of stink bugs is large.