Rutgers Cooperative Extension
Seasonal updates on diseases, insects, weeds impacting tree fruit and small fruit (blueberry, cranberry, and wine grape). Fruit Pest Alerts are also available via this category feed.
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Recent Rain Patterns and Insecticide Use:
Given our recent periods of rainy weather, many growers are questioning the need for repeated applications, and the weatherability of the materials already applied. Dr. John Wise at MSU has been studying the residual properties of insecticides for a number of years. [Read more…]
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Cranberry beds are in bloom. If insects have been effectively managed prior to bloom, we recommend no sprays at this time. A reminder: when bees are present your only choices of insecticides are insect growth regulators (IGRs) such as Intrepid 2F or Bt products such as DiPel.
During bloom we recommend monitoring insect populations using pheromone traps. Pheromone traps should be used particularly to monitor activity of Sparganothis fruitworm and blackheaded fireworm, two key pests in New Jersey.
Sparganothis fruitworm– Adult flight should have started a few weeks ago and we will be at peak flight activity by next week (see DD model
Sparganothis fruitworm adult
below). Damage by the second generation larvae begins after the eggs hatch, usually 9-12 days after they are laid. These larvae will feed on foliage and fruit. Larvae will partially feed on berries, causes scoring of the fruit. However, particularly on Ben Lear, larvae may feed inside the fruit. Insecticide treatment should target small larvae. Pheromone traps can be utilized to time insecticides sprays. If treatment is required, sprays should be applied two weeks after peak moth flight and/or earlier if using an IGR. If trap counts indicate a low population that requires management, a single insecticide application may be made post-bloom. If trap counts are high, then an early application of an IGR may be used when the first eggs start to hatch. This would be followed by a second application soon after bloom. Your post-bloom options are Diazinon, Altacor, Delegate, Exirel, or Intrepid.
As indicated above, controlling fruitworm populations is often very difficult and many require multiple applications depending on pest pressure. Sparganothis fruitworm populations in Massachusetts are resistant to organophosphate insecticides (e.g. Diazinon, Lorsban). Thus, organophosphates should be used with care, i.e., always rotate insecticides with different modes of action. Organophosphate insecticides will also negatively affect natural enemy populations. Delegate, Altacor, and Exirel are insecticides belonging to relatively new modes of action; these are registered against fruitworms and can be used as an alternative to organophosphates post-bloom.
Degree-day model for Sparganothis fruitworm
The figure details life history benchmarks of interest for Sparganothis fruitworm and associated degree-day estimates from March 1(credit:
Sparganothis degree-day benchmarks
Elissa Chasen and Shawn Steffan, USDA-ARS and UW Entomology). Flight initiation is predicted around 595 DD, at a lower temperature threshold of 50°F. Based on this model Sparganothis fight was initiated in our region (Chatsworth, NJ) about a week ago. So far, we have accumulated (starting April 15) 688 DD, which means that egg laying has just started (depending on the DD accumulations specific to your farm); however, eggs are not expected to hatch until later this month. Also, a reminder that a single insecticide application aimed at Sparganothis larvae will likely have the greatest effect if it is timed between the beginning and the peak egg-hatch/larval-emergence, which is approximately 895-1,400 DD. I will keep you updated on these DD predictions as the season progresses.
IPM guides for spotted wing drosophila (SWD) in blueberries and brambles are now available!
Download them from the Northeastern IPM Center website, provided below, or via the SWD IPM Working Group website, www.northeastipm.org/working-groups/spotted-wing-drosophila/.
Spotted Wing Drosophila IPM in Raspberries & Blackberries
http://www.neipmc.org/go/swdpub1
Spotted Wing Drosophila IPM in Blueberries
http://www.neipmc.org/go/swdpub2
Peach:
Plum Curculio (PC): PC oviposition should be done in all areas of the state, and there is up to 2-3% of fruit injury with egg scars. We have accumulated about 911 DD since petal fall (apple) in southern counties and just over 663 DD in Hunterdon County. The Cornell model calls for insecticides applied up to the 340 DD50 mark. Therefore, all sprays for this insect should be done. The model assumes a single generation in NJ, which is historically what we have had. New research from Anne Nielsen’s lab is telling us that the southern strain of PC is also present in the state. This is a multi-voltine strain, which means there is more than one generation per year in some parts of the state. Therefore with an early spring, we may see additional injury later in the season. [Read more…]
Based on our degree-day model for Sparganothis fruitworm, flight initiation is expected at around 596 DD (see chart). As of May 30,
Sparganothis degree-day model benchmarks
Sparganothis has accumulated 683 DD (using March 1 as biofix- a biofix used for the model) or 529 DD (using April 15 as biofix- a biofix more relevant to New Jersey cranberry cultural practices). This indicates that flight activity has just started or will start very soon. Growers are advised to place pheromone traps for monitoring this pest by this or next week, if they haven’t done so already.
