The spotted wing drosophila (SWD) is a new pest to California (since 2008). It's a small fly that attacks ripening cherries, and may also attack ripening raspberry, blackberry, blueberry, and strawberry crops, especially in coastal areas. When conditions are right, the fly can also attack soft-fleshed fruit such as plums, plumcots, nectarines, and figs.
If your cherry tree has SWD, you might notice that fruit flesh has one or more small punctures or “stings” on the surface. These symptoms are evidence of the eggs laid by the female SWD. Eggs will hatch into larvae (maggots) which feed inside on the fruit, causing brown and soft sunken areas that may exude fluid.
If you notice SWD in your fruit early enough, you can save some of the crop by harvesting it immediately and removing fruit with stings on the surface. Put infested fruit in a sturdy, sealed plastic bag and dispose of it in the trash. If you have fruit that isn't ripe yet, place fine netting around it to protect it.
Unfortunately, in many cases by the time you notice SWD damage, it may be too late. For information on how to make an apple cider vinegar trap and how to protect your fruit next season, see the UC IPM Pest Note: Spotted Wing Drosophila.
If your cherry tree has a different pest or problem, visit the UC IPM Cherries page to see a list of other pests, including diseases and environmental disorders.
- Author: Jian Long Bi
The seedcorn maggot (Delia platura) is a pest of many vegetable crops such as cabbage, broccoli, turnip, radish, onion, beet, spinach, pepper, potato, beans and peas. Maggots usually feed on germinating seeds, roots or stems, resulting in reduction of seedling stands and contamination of the crop. They also occasionally feed on head lettuce to make it unmarketable (the maggots damaging spring head lettuce were officially identified as seedcorn maggots. For more information, please visit http://ucanr.org/blogs/SalinasValleyAgriculture/index.cfm?start=16, Spring Head Lettuce Crop Affected by Insect, Thursday April 29 2010). The damage is especially severe during cool and wet winter or spring, and in fields with high organic matter. The feeding damage often causes secondary infections by pathogen.
The seedcorn maggot overwinters as pupa in soil. The adult emerges in early spring and a female can lay an average of 270 eggs in the soil near plant stems. The female prefers to lay eggs in fresh-tilled soil with high moisture and organic matter. The eggs hatch in a few days and the maggots feed for 1 to 3 weeks on decaying organic matter or their host plants before pupation in soil.
Prevention is the best management strategy for this pest. Any cultural practice to speed up seed germination and plant growth will help to reduce crop loss. Attach drag chains behind the planter during seeding can reduce egg laying in the seed row. Fields with heavy manure or cover crop should be plowed at least 2 weeks before planting. Fields with a history of seedcorn maggot problem may apply an insecticidal seed treatment at planting. After damage is observed on the crop, rescue treatments are usually not effective. Prompt resetting or replanting of the damaged crop may be necessary if stand loss is severe.
- Author: Steven T. Koike
- Author: Jian Long Bi
The spring growing conditions have been responsible for several problems that affected head lettuce in coastal California. Rain and cold temperatures have allowed significant development of bacterial leaf spot (Xanthomonas campestris pv. vitians) and a physiological disorder possibly related to tipburn. In addition, recent samples, received by UC Cooperative Extension, have been infested by an insect. Field personnel and pest control advisors have also been detecting this problem.
Underneath the wrapper leaves, inner layers are being fed upon by the larval stage (maggot) of a fly insect. Damage consists of holes and breaks in the leaves where the maggot has been feeding (photos 1, 2, 3).
Photo 1 |
Photo 2 |
Photo 3 |
Edges of the damaged areas turn tan to brown. Such feeding damage can occur anywhere along the leaf and midrib tissue. Careful examination of the inner leaves will likely reveal the presence of the maggot (photo 4) and/or the pupa (photo 5). Maggots are small (approximately 7 mm (1/10th inch) long) and pale in color.
Photo 4 |
Photo 5 |
The insect damage, which consists of actual holes in the tissue, is distinct from the physiological problem that typically does not result in breaks in the leaf and which is usually restricted to the leaf margins. The bacterial leaf spot disease affects mostly outer leaves and results in characteristically black lesions.
Identification of the fly is pending and Entomology Farm Advisor Jianlong Bi will be investigating this further.