Strawberries are now in the pre-harvest stage. They’re blooming and and just beginning to develop berries. Below is a bloom waiting on some pollinators to come along. To the left of it is a flower bud which has been pollinated and has just dropped its petals. This will grow up to be a strawberry.
Now is an important time to scout for insects. Spidermites and aphids are two we may see in abundance once the weather has warmed up. We should scout carefully for these because their populations can explode in a matter of days if conditions are right. Here is a photo of some aphids on a leaf.
For aphids, the threshold is 10 aphids per newly expanded leaf or excessive sooty mold is present. This doesn’t happen all that often. We usually have pretty good populations of beneficial insects to hold down the aphids. Below is an “aphid mummy” which is the dead body of an aphid that has been parasitized by a parasitic wasp. You can see the hole in the abdomen where the wasp emerged after developing within the body of the aphid.
Below is another beneficial insect: a lady bug (or more appropriately “lady beetle”) larva. Lady bugs that eat aphids and there are some species that eat mites, so these are great to have around.
Spidermites are even harder to see and usually require a hand lens. Though tiny they can be quite destructive. Powell Smith, Vegetable and Small Fruit Specialist with Clemson Extension recommends the following scouting method and threshold. In a field smaller than 5 acres look at 50 leaflets. In a field larger than 5 acres look at 100 leaflets. When over 4% of the leaflets are infested, treat with an effective miticide. Contact your local Extension Agent for help scouting for mites.
The photo above is a reminder of what else is going on in the field right now. Bees are pollinating the strawberries and we want to be careful not to harm them. Only spray insecticides when pest populations are above thresholds. When spraying is necessary, avoid doing so during the peak pollinating hours of 10 am to 2 pm. Instead, try spraying early in the morning or late in the evening when the bees are the least active. Sometimes it slips our minds that the same insecticides we’re spraying to kill pests may be harmful to the good insects as well.