IPM

Vegetable Problems Update

Maryland Grows2 Comments

Wildfire smoke

Persistent wildfire smoke is new for Maryland gardeners. Experts seem to agree that smoke and ash do not pose a health risk for garden produce. Smoke diffuses sunlight but will probably not significantly reduce the total amount of light for photosynthesis. We have not heard/seen any reports of gardeners picking up smoky flavors in harvested greens or other vegetables or fruits.

  • Wash all produce prior to eating it raw or cooking with it
  • Wear an N-95 quality mask when working outside on days when wildfire smoke worsens air quality
  • Hose off plants if a noticeable soot layer develops from prolonged, intense smoke

Wildfire smoke has been shown to boost the levels of ozone and other air pollutants which can injure plants. Watermelon, squash, pumpkin, beans, and potato are especially vulnerable to high ozone levels (above 75 ppb).

Drought and damaging storms

Wildfire smoke interfered with weather patterns and likely contributed to cooler and drier weather across much of the state. 

Mid-May through June:

  • Lower average temperatures
  • 75% of state in moderate drought on July 3rd
  • Slow start for warm-season crops

July:

  • High heat and humidity
  • Spotty rainfall
  • Insect and disease issues increasing
Maryland drought status map
The Maryland Department of the Environment announced a Drought Watch on July 10, encouraging voluntary reduction in residential water use.
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Biological pest control: parasitoids

Maryland Grows5 Comments

¿Hablas español? Aquí esta una traducción: Control biológico de plagas: los parasitoides

Parasitoids are natural enemies of pests that, like predators (ladybugs and flower flies) can help us keep pest populations at bay or eliminate them from our gardens.

Parasitoid or parasite? Let’s learn the difference between these terms

Before saying more about this group of natural enemies, let me tell you that it is very common to confuse the term “parasitoid” with the term “parasite.” Parasites and parasitoids have in common the need for a host for their development. The difference between the two types of organisms is that parasitoids kill their host to complete their life cycle. That is, the parasite can live at the expense of the host without having to kill it, while the parasitoid ends up killing its host upon completion of its life cycle. Parasites are generally known to be annoying and even transmit diseases to animals, plants, and humans, while parasitoids are beneficial insects, as they help us control pests.

What is a parasitoid?

Parasitoids are insects that insert their eggs into the body or egg of another insect (host) in order to complete their life cycle. Parasitoids go through complete metamorphosis, four different stages of development: egg, larva, pupa, and adult. To finish their development, the parasitoids must feed on their host, and the females first deposit their eggs in their host. As soon as the parasitoid egg hatches, the larvae begin to devour the tissues of their host. Once the larvae reach a certain size, they become pupae, after which the adult emerges, killing the host.

Parasitoids can be classified according to their oviposition (egg-laying) behavior. Endoparasitoids are the parasitoids that lay their eggs inside the body or egg of their host. In contrast, ectoparasitoids oviposit on top of the body of their host, that is, on the surface of their body. To see these fascinating creatures in action you can, watch a video of endoparasitoids and one of ectoparasitoid activity.

Life cycle of an ectoparasitoid (adapted from Presa-Barra et al 2020)

life cycle steps of an ectoparasitoid

Life cycle of an endoparasitoid (adapted from Presa-Barra et al 2020)

life cycle steps of an endoparasitoid
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