Japanese beetles have become one of the most detested insects of all time.  They are indiscriminate and feed on a multitude of vegetables, ornamentals, trees, and plants.  A lot of research is being conducted to combat these gregarious feeding insects.  There are options for control that depend on the plant being attacked, the amount of infestation and your level of time.   Note there are many websites that have the answer/product/cure/trap for Japanese beetles.  When researching online, find a trusted source, such as .edu or .gov or .org, that has actual research and not just anecdotal evidence.   Here are a couple of sources I have found to be updated on a timely basis and filled with fact-based information.
https://hnr.k-state.edu/extension/info-center/common-pest-problems/common-pest-problem-new/Japanese%20Beetles.pdf

https://extension.colostate.edu/topic-areas/insects/japanese-beetle-5-601/
​
http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/insects/beetles/japanese-beetle.aspx

Two diseases that attack tomatoes early in the growing season around blossom set are Early Blight and Septoria.  Both start on lower leaves of the plant and result in leaf spots that may eventually kill the leaf. Defoliation of the plant is harmful and also leads to sunscalded fruit.  Disease development is favored by warm temperatures, abundant rainfall and high humidity.  Mulching, caging, no overhead watering and good air flow are helpful to reduce disease pressures. To learn more about these early tomato diseases, here are articles from K-State Research and Extension and University of Minnesota.

https://hnr.k-state.edu/extension/info-center/common-pest-problems/common-pest-problem-new/Early%20Blight%20of%20Tomatoes.pdf

https://extension.umn.edu/diseases/early-blight-tomato

​http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/fungal-spots/septoria-leaf-spot-of-tomato.aspx
 

One of the first issues tomato growers experience is Tomato Leaf Roll.  It comes as a shock to gardeners as they are so happy that their tomato plant has grown quickly and looks great, then all of the sudden, bam.   I liken it to the awkward teenage years.   The plant’s top growth has outgrown the root growth.  The plant is out of balance, like an awkward teenager with disproportionate arms and legs.  The plant realizes it needs to cut back on leaf area for a bit to focus on root growth, so it rolls its leaves.  Some varieties have a tendency to do this more than others.   The condition corrects itself over a few weeks.  To learn more about it, here’s a link from K-State Extension and Research.
​
https://hnr.k-state.edu/extension/info-center/common-pest-problems/common-pest-problem-new/Tomato%20Leaf%20Roll.pdf
​