Fruit Development

Monitor for Asian citrus psyllid by conducting visual surveys of newly forming flush, and by using sweep net surveying or tap sampling. Manage according to the Citrus Pest Management Guidelines. In areas where Asian citrus psyllid Is not known to have established (central and northern California), if Asian citrus psyllid is found, contact your local county agriculture commissioner’s office, and report the location.

A CDFA liaison will provide research-backed information on Asian citrus psyllid management and coordinate treatments of commercial citrus.

Monitor California red scale males using pheromone-baited sticky traps, plus additional methods (e.g. calculate degree days, monitor crawler tapes, check scale infestations on fruit in the field, and examine harvested fruit).

• Distinguish male scales from scale parasites and other important insects caught in sticky traps.
• Begin checking fruit for scale infestation and percentage parasitism by Aphytis melinus and Comperiella bifasciata (August through October).
• Keep records (example red scale fruit count monitoring form—PDF).
• Release Aphytis melinus if biological control is compatible with the overall management program.

Monitor fruit for immature citrus thrips (late April through June).

• Keep records (example citrus thrips monitoring form (pdf) available online.
• Examine leaves for natural enemies, especially Euseius tularensis.

Manage if needed according to the Pest Management Guidelines.

Monitor fruit for immature citrus thrips (late April through June).

• Keep records (example citrus thrips monitoring form—PDF).
• Examine leaves for natural enemies, especially Euseius tularensis.

Manage if needed according to the Citrus Pest Management Guidelines.

Monitor leaves for citricola scale nymphs (late July–September).

• Be sure to distinguish citricola scale from brown soft scale.
• Keep records (example citricola scale monitoring form—PDF).

Manage if needed according to the Citrus Pest Management Guidelines.

Monitoring for cottony cushion scale. If significant live immature stages are still present in June, vedalia will not be effective at this time of year. Manage according to the Citrus Pest Management Guidelines.

If fruit are likely to be exported to Korea, then Fuller rose beetle is of concern:

• Estimate last season's levels of Fuller rose beetle in the block based on levels of egg masses found on harvested fruit or by looking inside the tree for the level of past leaf feeding (distinguish the jagged feeding of Fuller rose beetle from the rounder feeding of brown garden snails).
• Trees must be skirt-pruned 24 to 30 inches above the ground and maintained sufficiently to prevent tree skirts from contacting the ground from June until harvest.
• Weed control must be practiced sufficiently to prevent a bridge forming from the ground to the skirt from June until harvest.
• Determine current protocols for managing Fuller rose beetle in accordance with the Citrus Pest Management Guidelines.
• Maintain records of the above in case they are needed by the packinghouse or APHIS.

Look for citrus peelminer and examine fruit for its damage in susceptible citrus varieties such as grapefruit, pummelo, and Fukumoto oranges.

• Use degree-day units to predict the timing of infestations for susceptible varieties of citrus and manage according to the Citrus Pest Management Guidelines.

Monitor young citrus orchards (less than 5 years) for live citrus leafminer larvae in leaves. Manage according to the Citrus Pest Management Guidelines.

Look for other pests and their damage to fruit or damage to leaves and twigs, especially:

• European earwig (March through June)
• Forktailed bush katydid (March through June)
• Yuma spider mite (July through September)
• Kanzawa mite (August through September)
• Snails—estivating (dormancy period during hot, dry times) on fruit.

Manage if needed according to the Citrus Pest Management Guidelines.

Look for diseases that cause symptoms on fruit, leaves and twigs, and on limbs, trunks, and roots, especially:

• Dry root rot
• Hyphoderma canker (mainly in lemons)
• Phytophthora gummosis and Phytophthora root rot

Record the date and location of problem trees or sites. Manage if needed according to the Citrus Pest Management Guidelines.

Survey summer weeds. Identify common summer broadleaves and grasses and sedges.

• Keep records (example summer weed survey form—PDF); survey at least twice annually (during late winter and in summer).
• Look for and remove favored weed hosts of bean thrips if navels might be exported to Australia.

Manage vegetation if needed according to the Citrus Pest Management Guidelines.

Look for vertebrates, especially ground squirrels, pocket gophers, rabbits, and roof rats. Manage if needed according to the Citrus Pest Management Guidelines.

Provide proper cultural care and good growing conditions to improve tree health and fruit yield, including:

• Sample leaf nutrient levels at least once from mid-August through October. Fertilize if needed.
• Irrigate and adjust scheduling to meet trees' varying water needs.
• Prune if needed and skirt-prune lower branches to reduce brown rot.

Determine whether application of plant growth regulator is warranted. Consider

• Gibberellic acid (GA3) to prevent fruit senescence in grapefruit, limes, navels, pummelo, tangerine (mandarin) hybrids, and Valencias.
• 2,4-D to reduce preharvest fruit drop, rind staining, water spot, and sticky rind of navels, Valencias, grapefruit, lemons, tangelos, and other citrus hybrids.