Cooperative Extension San Joaquin County
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Cooperative Extension San Joaquin County

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Jumping oak galls on valley oaks

This time of year, it is not uncommon to see the valley oak trees (Quercus lobata) with their leaves yellowed and splotchy with numerous small seed like balls on the underside.  These are called Jumping oak galls and they are made by a small Cynipid wasp larva (Neuropterus saltatorius) that is developing inside the gall.  Don’t worry-the wasp doesn’t sting humans.  In fact, you would be lucky to actually see the critter.  While the galls do cause some defoliation, they are not particularly harmful to the trees.  They may cause some serious leaf loss in some years and this year seems to be one of those years.  The adult female wasp, in order to be able to create a gall that contain an egg, must sting the leaf at precisely the right time.  If the leaves are too fully expanded and hardened off, the galls will not form.  That is why you might see one tree with millions of these galls and yet the one nearby might not have any.  Their foliation times may be somewhat different.  There are many types of oak galls including yhose that look like chocolate kisses and some that look like apples, and still others that look like horned or fuzzy balls.  We do not normally recommend any type of control of these insects.  However, some research indicates that if one leaves the infested leaves on the ground, the parasites of these little wasps are not raked away and it may moderate the population over time.  As well, there is more “mulch” on the ground around the trees, which is a good thing.   

One of the fun things to do with the galls as they are beginning to fall off the tree is to just bring them into the house.  As the galls warm, they begin to jump and wiggle around and make a snap crackle and pop noise….

To Learn More….

Posted on Monday, August 3, 2009 at 11:41 AM
Tags: Oaks (5), Pest (4), Quercus (1), Trees (2)

How Can I Control Creeping Wood Sorrel (Oxalis) in My Lawn?

  The lawn, from a distance, looks lush and green.  When walking across it, however, the exploding seed pods of the densely growing oxalis spread seeds across my boots and across my lawn.  In one year the newly planted cool season turfgrass has become an oxalis or creeping wood sorrel lawn. 

Creeping woodsorrel is a major weed in turf, ornamental plantings, gardens, and nurseries. Uninfested landscapes can become contaminated if infested container stock is used in plantings. As seed pods mature and expel seeds, creeping woodsorrel spreads from container to container, flower bed to flower bed, or across ornamental plantings and lawns....

Learn More.....

Posted on Tuesday, July 28, 2009 at 3:24 PM
Tags: herbicides (1), lawn (3), oxalis (1), turf (2), weeds (12)

Aphids in My Cantaloupes!!!

I have been growing the most wonderful variety of cantaloupes called “Athena” in my vegetable garden.  This variety is to die for….sweet, firm, and longer lasting than the Tuscan varieties.  The vines were vigorous, productive and gorgeous until the aphids moved in and started curling the leaves and excreting honeydew, making everything a sticky mess.  I am partly to blame because I watched the small aphid population just explode to a huge problem.  I knew I should have done something early on but I didn’t….my excuse was not enough time in the day.  Nonetheless, there was also a large population of both ladybugs and parasitic wasps that I thought might do the job for me so I really didn’t want to spray a pesticide.  Now the big question is, is it too late and will it matter to my melon harvest?  

Conventional wisdom says that aphid populations will drop when temperatures go above 100F.  Well, we reached that number and then some so that is one reason to hope that the melon harvest can be saved.  The second thing is that there are lots of predators and parasites available to help munch those hardy aphids that continue to survive despite the temperatures.  What else could one do to manage aphids to save the melon?  Well, here is my list and I am going to do these things because the reward of these perfect melons is a great motivator.

  1. Hose off the plants with a strong stream of water.  This will clean up a lot of the honeydew and reduce the numbers of aphids on the plant. Do this in the early part of the day to avoid water droplets on the leaves during the hot part of the day.  Spray them off daily if possible. 
  2. When temperatures drop below 90F during the day, spray with an insecticidal soap, neem oil or summer weight oil and cover the undersides of the leaves as much as possible.  These materials may be phytotoxic (cause damage) to some plants, so check labels and test them out on a portion of the foliage several days before applying a full treatment. These materials are considered least toxic materials and do not harm most beneficial insects that may be found on the plants.
  3. Where there is heavily curled foliage, prune that off to reduce the numbers of aphids that are inside the curled foliage protected from both predators and parasites and any water or pesticide sprays.
  4. Plan to go to the farmer’s market for great melons if my plan doesn’t work…..


For more information on aphid management in  your garden go to: to learn more.

Posted on Monday, July 20, 2009 at 10:27 AM

What should I be doing during the summer for my peach trees?

Summer is an important time not only for fruit harvest but also for insuring a good crop in subsequent years.  For example, typical summer fertilizing calls for:

Summer Growing Season

  • Fertilize young trees monthly. Use 0.5 lb. urea or 25 lb. manure/tree/appl. Mature trees need 50% more. Water fertilizer in. If drip irrigated, do not exceed 1 oz. urea/emitter/mo.
  • Drip irrigate daily or sprinkler irrigate about every 3 weeks.
  • Maintain a weed free area around the base of the trees within 3' of the trunk with an organic mulch 3–4" deep.

Learn More.....

Posted on Tuesday, July 14, 2009 at 3:15 PM

Fruit Tree Workshop at Wolfskill Ranch, Winters, CA

We’ve got an exciting program coming up on August 14 at the Wolfskill Experimental Orchard.  Spend the day with us learning about creating and maintaining sustainable home orchards of any size.  We’ll be tasting fruit, offering a hands-on demonstrations, touring Wolfskill and much more!  Your registration of $45 includes lunch, fruit tastings and a pomegranate plant. 

Please join us – you’ll leave prepared to start your own backyard fruit production!  You can pay by credit card, download the flier, agenda and directions at  See you there.

Posted on Monday, July 13, 2009 at 9:00 AM

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